bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen evolution by subchloroplast preparations of photosystem II from pea and spinach
Authors: Mal'tsev Sergey V. , Allakhverdiev Suleyman I. , Klimov Vyacheslav V. , Krasnovsky Alexander A.
Published: July 2002

Hydrogen (H2) evolution rates were measured by the gas chromatographic technique upon illumination of different subchloroplast preparations of higher plants without exogenous hydrogenase under anaerobic conditions. Subchloroplast preparations enriched in photosystem II (PS II) in the presence of an electron donor TMPD (N,N,N′,N′‐tetramethyl‐p‐phenylenediamine) are shown to have higher H2‐evolution rates (up to 30 nmol/mg Chl per h) than preparations enriched in PS I under the same conditions. The data on the suppression of H2 evolution by well‐known inhibitors of PS II (dinoseb, atrazine) prove that the H2 photoproduction is sensitized by PS II reaction centers.
The low activity of acetyl‐CoA car☐ylase in basal and glucagon‐stimulated hepatocytes is due to phosphorylation by the AMP‐activated protein kinase and not cyclic AMP‐dependent protein kinase
Authors: Sim Alastair T.R. , Hardie D.G.
Published: July 2002

Acetyl‐CoA car☐ylase purified from isolated hepatocytes is activated dramatically by protein phosphatase treatment, concomitant with a reduction of the phosphate content from 3.7 to 1.1 mol/subunit. Glucagon treatment of the cells produces a further inactivation of the enzyme that is totally reversed by phosphatase treatment, and is associated with an increase in phosphate content of 0.8 mol/subunit, distributed in two peptides which contain the sites phosphorylated in vitro by the cyclic AMP‐dependent and AMP‐activated protein kinases. Sequencing of these peptides shows that the low activity of acetyl‐CoA car☐ylase is due to phosphorylation by the AMP‐activated protein kinase, and not cyclic AMP‐dependent protein kinase, even after glucagon treatment.
Partial separation of inwardly pumping and outwardly pumping bacteriorhodopsin reconstituted liposomes by gel filtration
Authors: Seigneuret Michel , Rigaud Jean-Louis
Published: July 2002

Reconstitution of bacteriorhodopsin using the reverse‐phase evaporation technique leads to the formation of both inwardly proton pumping and outwardly proton pumping liposomes [(1985) FEBS Lett. 188, 101–1061]. The reconstituted preparation was size fractionated using gel filtration chromatography on Sephacryl S1000. The direction of proton pumping was assessed in various fractions using the pH sensitive fluorescence probe pyranine. The proportion of outwardly pumping liposomes was shown to increase with decreasing liposome size. The larger liposomes (diameter larger than 200 nm) were shown to be pure inwardly pumping liposomes with almost homogeneous bacteriorhodopsin orientation.
Calcium channels in undifferentiated PC12 rat pheochromocytoma cells
Authors: Janigro Damir , Maccaferri Gianmaria , Meldolesi Jacopo
Published: July 2002

Undifferentiated rat pheochromocytoma PC12 cells were voltage clamped using the whole cell technique. After blockade of outward currents, calcium currents were elicited from −40 and −100 mV. A subpopulation of cells displayed only one current component activated at −10 mV and slowly decaying. In other cells this current coexisted with a component activated around −40 mV and decaying with a faster time constant. We conclude that undifferentiated PC12 cells can express two types of calcium channels, L (long‐lasting) and N (neuronal)‐type channels.
Maturation of nuclear lamin A involves a specific carboxy‐terminal trimming, which removes the polyisoprenylation site from the precursor; implications for the structure of the nuclear lamina
Authors: Weber Klaus , Plessmann Uwe , Traub Peter
Published: July 2002

Lamin A, a nuclear lamina protein of differentiated cells, is synthesized as a precursor of the mature molecule. Protein sequencing of the carboxyterminal 14 kDa fragment shows a lack of the last 18 residues predicted by cDNA sequencing. The carboxy‐terminal proteolytic maturation explains previous biochemical results including the loss of the polyisoprenylation site now located to the CXXM motif at the end of the chain. This view and earlier results on lamin B predict multiple post‐translational modifications shared by lamins A and B. While retained by lamin B, which is present in all cells, they are lost by maturation from lamin A, which probably acts only as an additional lamina constituent in differentiated cells.
HSV infection induces increased transcription of Alu repeated sequences by RNA polymerase III
Authors: Jang K.L. , Latchman D.S.
Published: July 2002

The Alu family of repeated sequences is transcribed by both RNA polymerase II and RNA polymerase III. In cells infected with HSV, transcription by polymerase III increases while transcription by polymerase II decreases. By using virus strains carrying mutations in the genes encoding individual regulatory proteins, we have shown that this effect is dependent upon the immediate‐early protein ICP27 and occurs by a process distinct from those which regulate viral gene expression. This is the first example of increased transcription of endogenous cellular sequences by RNA polymerase III during infection with a DNA virus.
Short and long spacer sequences and other structural features of zinc binding sites in zinc enzymes
Authors: Vallee Bert L. , Auld David S.
Published: July 2002

Metalloenzyme; Metalloproteinase; Zinc; Amino acid spacer sequence
Inhibition of insulin secretion by interleukin‐1β and tumour necrosis factor‐α via an L‐arginine‐dependent nitric oxide generating mechanism
Authors: Southern C. , Schulster D. , Green I.C.
Published: July 2002

Inhibition of glucose‐induced insulin secretion by interleukin‐1β (IL‐1β), or IL‐1β plus tumour necrosis factor‐α (TNF‐α), was less marked when rat islets of Langerhans were cultured for 12 h with these cytokines in L‐arginine‐free medium as opposed to medium containing L‐arginine (1 mM). Inhibition of secretion by IL‐1β was further alleviated when islets were maintained in L‐arginine‐free medium supplemented with N‐ω‐nitro‐L‐arginine methyl ester (NAME), while synergism between IL‐1β plus TNF‐α was completely abolished. Tissue culture medium nitrite levels were raised in islets treated with IL‐1β or TNF‐α (48 h). Cytokine‐stimulated nitrite production was not observed in islets cultured with NAME (1 mM). In conclusion, an L‐arginine‐dependent nitric oxide generating mechanism is involved in the inhibition of insulin secretion by IL‐1β, and accounts for the phenomenon of synergism between IL‐1β and TNF‐α.
Activation of red cell Ca2+ ‐activated K+ channel by Ca2+ involves a temperature‐dependent step
Authors: Varečka Ĺudovít , Peterajová Elena
Published: July 2002

We found that vanadate‐induced 45Ca2+ uptake by red cells is maximal at 25°C. At this temperature, the Cai‐induced increase of the K+ permeability (the Gardos effect) shows a lag (up to 8 min) which is not observed at 37°C. This cannot be explained by the lack of availability of Ca2+ for the Ca2+‐activated K+ channel, and suggests that its activation by Ca2+ is mediated by a temperature‐dependent mechanism which remains unknown so far. The lag is not observed when the Gárdos effect was initiated by propranolol. This shows that the putative temperature‐dependent step is different from chloride transport.
The effect of salt on the Michaelis Menten constant of the HIV‐1 protease correlates with the Hofmeister series
Authors: Wondrak Ewald M. , Louis John M. , Oroszlan Stephen
Published: July 2002

The effect of different types of salt on the proteolytic activity of HIV‐1 protease was studied. At a similar ionic strength, the enzyme activity changed according to the salting out effect of the ions used (Hofmeister series). Kinetic studies showed that a stronger salting out effect of the ions rather than the higher ionic strength per se increased the affinity to the substrate (Km
) but in general did not alter the K
cat value.
Involvement of a serine esterase in oxidant‐mediated activation of phospholipase A2 in pulmonary endothelium
Authors: Chakraborti Sajal , Michael John R.
Published: July 2002

Exposure of bovine pulmonary arterial endothelial cells to 1 mM H2O2 stimulated associated TAME‐esterase and PLA2 activities. Pretreatment with the serine esterase inhibitors: PMSF (1 mM), DFP (1 mM), and α1‐PI (1 mg/ml) inhibited H2O2‐induced stimulation of TAME‐esterase and PLA2 activities. The TAME‐esterase and PLA2 activities under H2O2 exposure were determined to be linearly correlated. Affinity labeling of the endothelial cell membrane with [3H]DFP demonstrated that the serine esterase resides in a protein having molecular weight of 29000 daltons (29 kDa) which is similar to that of elastase. Treatment of the endothelial cell homegenate with trypsin (1 μ/ml) also stimulated PLA2 activity.
Carotenoid composition in the cyanobacterium Phormidium laminosum Effect of nitrogen starvation
Authors: Fresnedo Olatz , Gomez Ramón , Serra Juan L.
Published: July 2002

When pigments of the non‐N2‐fixing cyanobacterium Pharmidium laminosum were carefully extracted and analyzed in a completely O2‐free atmosphere, by either high performance liquid chromatography (HPLC) or thin layer chromatography (TLC) , the presence of only two carotenoids (namely, β‐carotene and nostoxanthin) was detected. However, exposure of pigments to an air atmosphere during their manipulation led to the rapid appearance in the organic extracts of at least three additional carotenoids (identified as caloxanthin, zeaxanthin and β‐cryptoxanthin). This fact could explain in the presence in cyanobacteria of such hydroxylated acrivatives of β‐carotene widely reported in the literature. Nitrogen starvation also resulted in an important decrease on the relative β‐carotene/nostoxanthin content of cells, suggesting that this nutritional condition affects thylakoid membranes more drastically than cytoplasmic membranes.
Possible involvement of superoxide anion in the induction of cyanide‐resistant respiration in Hansenula anomala
Authors: Minagawa Nobuko , Koga Satoshi , Nakano Minoru , Sakajo Shigeru , Yoshimoto Akio
Published: July 2002

A chemiluminescence study showed that Qi site inhibitors such as antimycin A induce O2
− generation in respiring cyanide‐sensitive mitochondria from the yeast, Hansenula anomala. The O2
− generation was suppressed by radical scavengers such as flavone, butylated hydroxyanisole, and Co0. Induction of cyanide‐resistant respiration in H. anomala cells by Qi site inhibitors was also inhibited by these radical scavengers. Furthermore, antimycin A‐induced synthesis of the mitochondrial 36‐kDa protein, which is thought to be the alternative oxidase functional in the cyanide‐resistant respiratory pathway, was abolished by the addition of flavone. These observations suggest that O2
− is somehow involved in the induction of cyanide‐resistant respiration.
Cyclin A‐Cys41 does not undergo cell cycle‐dependent degradation in Xenopus extracts
Authors: Lorca Thierry , Devault Alain , Colas Pierre , Van Loon André , Fesquet Didier , Lazaro Jean Bernard , Dorée Marcel
Published: July 2002

Truncated cyclin A and cyclin B lacking the N‐terminal domain comprising the ‘destruction box’ escape from proteolysis and arrest cells at metaphase. Mutation of a conserved arginine residue or the destruction domain makes cyclin B resistant to proteolysis, Here we show that mutation of the same residue also makes cyclin A resistant to proteolysis. in either of two situations in Which the cyclin degradation pathway is turned on: (i) in Xenopus extracts of activated eggs where the degradation pathway has been permanently turned on by adding a recombinant undegradable cyclin B in which the arginine residue of the destruction box has been substituted by alanine; (ii) in extracts of metaphase II‐arrested oocytes after Ca2+‐dependent inactivation of the cytostatic factor (CSF).
Identification of the three major coeliac immunoreactive proteins and one α‐amylase inhibitor from oat endosperm
Authors: Rocher Asuncion , Colilla Francisco , Ortiz Maria Luisa , Mendez Enrique
Published: July 2002

Six chloroform/methanol‐soluble proteins from oat endosperm (Avena sativa) have been isolated and characterized by a purification procedure based on extraction with volatile solvents, followed by reversed‐phase high performance liquid chromatography. Three of these proteins, with an assessed molecular weight of 25,000, 27,000 and 32,000 Da, respectively, have been identified by immunoblotting using coeliac sera, as the major coeliac serum IgA‐binding components of oat endosperm. The N‐terminal amino acid sequence of these proteins indicates that they correspond to α2, γ4, and γ3 avenins, respectively. We have tentatively named them ‘coeliac immunoreactive proteins’. Another chloroform/methanol oat component shows weak α‐amylase inhibitory activity and exhibits strong homology (60% identity) at the N‐terminus with the α‐amylase inhibitor from ragi (Eleusine coracana).
Evidence for new phosphorylation sites for protein kinase C and cyclic AMP‐dependent protein kinase in bovine heart 6‐phosphofructo‐2‐kinase/fructose‐2,6‐bisphosphatase
Authors: Rider Mark H. , Van Damme Josef , Vertommen Didier , Michel Alain , Vandekerckhove Joël , Hue Louis
Published: July 2002

Bovine heart 6‐phosphofructo‐2‐kinase/fructose‐2,6‐bisphosphatase (PFK‐2/FBPase‐2) was phosphorylated by incubation with [γ‐32P]MgATP and cyclic AMP‐dependent protein kinase (PKA) or protein kinase C (PKC). After digestion with chymotrypsin, the phosphorylation sites for the two protein kinases were identified by peptide mapping, and microsequencing. Evidence for new phosphorylation sites for PKA (Ser‐483) and PKC (Ser‐84 and Ser‐466) was obtained.
Investigation of the neighbour relationships between photosystem II polypeptides in the two types of isolated reaction centres (D1/D2/cytb559 and CP47/D1/D2/cyt b559 complexes)
Authors: Moskalenko Andrey A. , Barbato Roberto , Giacometti Giorgio M.
Published: July 2002

The nearest neighbour relationships within the D1/D2/cyt b
559 complex (PSIIRC) and the CP47/D1/D2/cyt b
559 complex (RC‐CP47) were investgated by using different length bifunctional crosslinking agents. The crosslinking products were identified by immunoblotting with polyclonal antibodies and by two‐dimensional gel electrophoresis. Seven products (CP47/D2, D1/D2/α, D1/D2, D2/α, D1/α, α/αa, α/β) have been revealed in both complexes. The crosslinking of both complexes does not increase their photostability. The photocrosslinking products (D1/α and D2/α) appeared under illumination of complexes with light of high intensity.
Sucrose synthase genes in barley
Authors: de Ilarduya Oscar Martinez , Vicente-Carbajosa Jesus , de la Hoz Pilar Sanchez , Carbonero Pilar
Published: July 2002

A cDNA of 2,708 bp encoding type 2 sucrose synthase (Ss2) from barley has been sequenced. Similarity of this cDNA with respect to that of type 1 (Ss1) is high in the coding region (75% identical positions), but low (41% identical residues) in the 3' non‐coding region. Type‐specific non cross‐hybridizing probes for Northern blot analysis have been obtained from the 3' ends. The Ss1 type is highly expressed in developing endosperm and in roots and, at lower levels, in coleoptiles and aleurone. The Ss2 mRNA is abundant in endosperm, low in aleurone, and undetected in coleoptiles and roots.
Human lymphocyte antigen CD38 catalyzes the production of cyclic ADP‐ribose
Authors: Summerhill Robin J. , Jackson David G. , Galione Antony
Published: July 2002

The human lymphocyte antigen CD38 has been shown to share sequence homology with ADP‐ribosyl cyclase, the enzyme that catalyzes the conversion of NAD+ to cyclic ADP‐ribose (cADPR), a potent Ca2+‐mobilizing agent. In this study COS1 cells from African Green Monkey kidney were transiently transfected with CD38 cDNA, inducing expression of authentic CD38 on the cell surface. We demonstrate that CD38 expressed in this manner can convert NAD+ to cADPR in the extracellular medium as assessed by Ca2+ release from sea‐urchin egg microsomes.
Interleukin 4 inhibits the production of some acute‐phase proteins by human hepatocytes in primary culture
Authors: Loyer Pascal , Ilyin Gennady , Razzak Ziad Abdel , Banchereau Jacques , Dezier Jean-François , Campion Jean-Pierre , Guguen-Guillouzo Christiane , Guillouzo André
Published: July 2002

Interleukin 4 (IL4) has been shown to exhibit anti‐inflammatory effects by inhibiting the secretion by monocytes of proinflammatory cytokines such as interieukin 1 (IL1), interleukin 6 (IL6), and tumor necrosis factor (TNF) and by inducing the secretion of the IL1 receptor antagonist. We investigated the role of this cytokine on the production of acute‐phase proteins in primary human hepatocyte cultures. Cells were exposed to either IL4 and/or IL6, the most potent mediator of hepatic acute phase proteins. IL4 led to decreased production of haptoglobin, C‐reactive protein and albumin while α1‐antitrypsin and fibrinogen remained unaffected. These inhibitory effects of IL4 were also observed at the mRNA level. In addition, IL4 inhibited the IL6‐induced production of haptoglobin although it had no effect on the induced C‐reactive protein and fibrinogen. Our results demonstrate that IL4 can affect the production of a subset of acute‐phase proteins by human hepatocytes and can antagonize some of the effects of IL6. These observations reinforce the notion that IL4 can be considered as an anti‐inflammatory cytokine.
TRP‐1 expression correlates with eumelanogenesis in human pigment cells in culture
Authors: del Marmol V. , Ito S. , Jackson I. , Vachtenheim J. , Berr P. , Ghanem G. , Morandini R. , Wakamatsu K. , Huez G.
Published: July 2002

We have investigated the relationship in human cultured normal and malignant melanocytes between the accumulation of mRNAs encoding tyrosinase and tyrosinase‐related protein‐1 (TRP‐1), the activity of tyrosinase and the presence of melanin. Tyrosinase mRNA correlates with tyrosinase activity and with the presence of pheomelanin, eumelanin or both melanin types. In contrast TRP‐1 mRNA is only detectable in cells containing eumelanin, which suggests a role for TRP‐1 in the eumelanin synthesis pathway.
Distribution of β2‐adrenergic receptor mRNA expression along the hamster nephron segments
Authors: Taniguchi Shigeo , Watanabe Tsuyoshi , Nakao Akihide , Seki George , Uwatoko Shu , Suzuki Keiji , Kurokawa Kiyoshi
Published: July 2002

Distribution of β2‐adrenergic receptor mRNA expression along the microdissected hamster nephron segments was examined by the reverse transcription‐polymerase chain reaction (RT‐PCR) technique. Conventional RT‐PCR using a set of primers on separate exons could not be applied for the detection of β2‐adrenergic receptor mRNA because of its intronless nature. We used the ‘rapid amplification of cDNA ends’ protocol [(1985) Proc. Natl. Acad. Sci. USA 85, 8998‐9002] as a maneuver for RT‐PCR of an intronless gene. Using this method, we successfully located hamster β2‐adrenergic receptor mRNA only in glomeruli and early proximal convoluted tubule along the nephron segments tested.
Purification and partial characterisation of NADP+‐linked isocitrate dehydrogenase from rat liver cytosol
Authors: Fatania Hasmukh , Al-Nassar Khaled Eid , Sidhan Vasantha
Published: July 2002

NADP+‐linked isocitrate dehydrogenase from rat liver cytosol was purified (approximately 135‐fold) to apparent homogeneity in 27% yield. The purified enzyme has specific activity of 73 units · mg− 1. The native enzyme showed an apparent M
r of 94,000 by gel filtration and was composed of two identical subunits of M
r 45,000 as judged by SDS/PAGE. In isoelectric focusing, a pI value of 5.7 was estimated for the enzyme.
Functional expression and purification of the ABC transporter complex associated with antigen processing (TAP) in insect cells
Authors: Meyer Thomas H. , van Endert Peter M. , Uebel Stephan , Ehring Bettina , Tampé Robert
Published: July 2002

Using the baculovirus expression system the gene products of human tap1 and tap2 were over‐expressed as wild‐type as well as oligohistidine fusion proteins in Spodoptera frugiperda (Sf9) insect cells. Both gene products were co‐expressed within the same cells and were found enriched in microsomal membranes. Immunoprecipitation and immobilized metal affinity chromatography revealed complex formation between TAP1 and TAP2. The expressed TAP complex was shown to be functional by peptide translocation into microsomes of Sf9 cells. Peptide transport strictly requires TAP1 and TAP2 as well as ATP. For the first time the functional expression of the human TAP complex in insect cells has been demonstrated, indicating that additional cofactors of a highly developed immune system are not essential for peptide transport across microsomal membranes.
Sequence‐specific hypomethylation of the tobacco genome induced with dihydroxypropyladenine, ethionine and 5‐azacytidine
Authors: Kovav̌ík A. , Koukalová B. , Holý A. , Bezdĕk M.
Published: July 2002

Higher plant DNA is methylated at CG and CNG targets. In this study we have investigated the tobacco methylation system in tissue culture using the methylation inhibitors 5‐azacytidine (5‐azaC), dihydroxypropyladenine (DHPA) and ethionine (Ethi), and methylation‐sensitive restriction endonucleases HpaII, MspI, HhaI, EcoRII, ScrFI, and Fnu4HI. Surprisingly, CAG/CTG sequences, contrary to CG doublets and CCG/CGG triplets, appeared to be refractory to the inhibitory effect of 5‐azaC. Thus 5‐azaC cannot be considered a general inhibitor of DNA methylation in tobacco cells. On the other hand, DHPA, the inhibitor of S‐adenosylhomocysteine (SAH) hydrolase, and Ethi caused hypomethylation of both CAG/CTG and CCG/CGG triplets but not of the CG doublets. The sensitivity of triplet‐specific methylation to the inhibition of SAH hydrolase suggests the possibility that plant‐specific DNA methylation at CNG targets might be modulated by alterations of the SAH/S‐Adenosyhnethionine ratio in plant cells.
Specific amino acid substitutions in human collagenase cause decreased autoproteolysis and reveal a requirement for a second zinc atom for catalytic activity
Authors: Williams D.H. , Murray E.J.
Published: July 2002

We have previously reported the crystal structure of truncated human collagenase (domain II) complexed with a low molecular weight inhibitor. Attempts to crystallise full‐length active collagenase (i.e. domain II + III) have been hindered by autoproteolysis at the domain II/III junction at high protein concentrations. To overcome this problem, we have generated an inactive enzyme via a H149 → L,D151 → N double substitution which displaces the non‐catalytic zinc atom, and shown that the altered collagenase is unable to cleave a synthetic substrate. We have also generated an I251 → S substitution at the domain II/III junction and demonstrate an increased resistance to proteolysis compared to wild‐type collagenase.
PRE3, highly homologous to the human major histocompatibility complex‐linked LMP2 (RING12) gene, codes for a yeast proteasome subunit necessary for the peptidylglutamyl‐peptide hydrolyzing activity
Authors: Enenkel Cordula , Lehmann Heike , Kipper Julia , Gückel Roland , Hilt Wolfgang , Wolf Dieter H.
Published: July 2002

20S proteasomes are multifunctional proteinase complexes ubiquitous in eucaryotes. We have cloned the yeast PRE3 gene by complementation of the pre3‐2 mutation, which leads to a defect in the peptidylglutamyl‐peptide hydrolyzing activity of the 20S proteasome. The PRE3 gene, a β‐type member of the proteasomal gene family, is essential for cellular life and codes for a 193‐amino acid proteasomal subunit with a predicted molecular mass of 21.2 kDa. The Pre3 protein shows striking homology to the human proteasome subunits Hsδ and Lmp2 (Ring12). Lmp2 is encoded in the major histocompatibility complex class II region implicating proteasomes in antigen processing.
NMR structures of ferredoxin chloroplastic transit peptide from Chlamydomonas reinhardtii promoted by trifluoroethanol in aqueous solution
Authors: Lancelin Jean-Marc , Bally Isabelle , J. Arlaud Gérard , Blackledge Martin , Gans Pierre , Stein Mariana , Jacquot Jean-Pierre
Published: July 2002

The 32‐amino acid transit peptide of the unicellular green alga Chlamydomonas reinhardtii ferredoxin has been synthesized and analysed by NMR spectroscopy and circular dichroism. The results show that while the peptide is unstructured in water, it undergoes an α‐helix formation from residue 3 to 13 in a 30:70 molar‐ratio mixture of 2,2,2‐trifluoroethanol. The remainder of the peptide is still unstructured in CF3CD2OD/H2O mixtures, but is distributed on a side opposite to a hydrophobic ridge formed by Met5, Phe9 and Val13 on the induced a‐helix. The NMR structures driven by 2,2,2‐trifluoroethanol in aqueous solution, are discussed in terms of potent interactions with the chloroplast envelope and its translocation molecular machinery.
Furin is important but not essential for the proteolytic maturation of gp160 of HIV‐1
Authors: Gu MiLi , Rappapor Jay , Leppla Stephen H.
Published: July 2002

The envelope glycoproteins of HIV are required for viral infectivity. Proteolysis of the precursor envelope glycoprotein gp160 results in the formation of gp120 and gp41. Cleavage occurs after the sequence Arg‐Glu‐Lys‐Arg. This sequence is expected to be a substrate for the cellular protease furin. We examined whether furin is responsible for cleavage of gp160 by using a furin‐deficient CHO cell line and the same cell line transfected with furin cDNA. Data obtained from viral transmission assays suggested that furin increased viral infectivity but was not essential for the maturation of gp160, implying that other proprotein processing enzymes also recognize this putative furin cleavage site.
Correlated behavior of the EPR signal of cytochrome b‐559 heme Fe(III) ligated by OH− and the multiline signal of the Mn cluster in PS‐II membrane fragments
Authors: Fiege Rober , Shuvalov Vladimir A.
Published: July 2002

EPR signals of Cyt b‐559 heme Fe(III) ligated by OH− and the multiline signal of the Mn cluster in PS‐II membrane fragments have been investigated. In 2,3‐dicyano‐5,6‐dichloro‐p‐benzoquinone‐oxidized PS‐II membrane fragments the light‐induced decrease of the EPR signal of the heme Fe(III)‐OH− is accompanied by the appearance of the EPR multiline signal of the Mn cluster. Addition of F− ions, which act as a stronger ligand for heme Fe(III) than OH−, decreases to the same extent the dark‐ and light‐induced signal of the heme Fe(III)‐OH− and the light‐induced multiline signal of the Mn cluster. These results are discussed in terms of the light‐induced formation of a bound OH′ radical shared between the Cyt b‐559 heme Fe and the Mn cluster as a first step of water oxidation.
The induction of neurotrophin and trk receptor mRNA expression during early avian embryogenesis
Authors: Baig M.A. , Khan M.A.
Published: July 2002

Nerve growth factor, brain‐derived neurotrophic factor and neurotrophin‐3, designated neurotrophins, are a family of neurotrophic factors, having important functions in the survival of embryonic and adult neuronal subpopulations. Through the trk family of receptors, these neurotrophins utilize phosphotyrosine‐mediated signal transduction. We have used RT‐PCR to detect the expression of mRNA for the above neurotrophins and their respective receptors, namely trkA, trkB and trkC in embryonic stages 1–8 of chicken development. While trkA and trkC mRNAs were expressed from stage 1 onwards, NGF and NT‐3 mRNAs were expressed only at stages 3 and 5, respectively. In contrast, BDNF mRNA was expressed at stage 1, being the only neurotrophin expressed prior to expression of its respective receptor trkB. However, the latter was not expressed until stage 8. These results indicate an earlier expression of some but not all trk proto‐oncogenes, suggesting that the two different receptor mRNAs expressed i.e. trkA and trkC in conjunction with BDNF, at stage 1, may act in aspects of very early embryonic development, such as gastrulation. Thereafter, mRNAs for trkB, NGF and NT‐3 are expressed reflecting their later action in early embryonic development.
The birth of the bipolar disorder
Authors: Pichot P
Published: July 2002

The history of the description by Jean-Pierre Falret of circular insanity, the origin of our present day bipolar disorder, is presented as well as the claims of priority raised by his colleague Jules Baillarger. A detailed account is given of the long-lasting controversy which has often given rise to biased judgments about the respective roles of the two psychiatrists. It is shown that the clinical concept was an expression of Falret's views about the nature of mental disorders and that, through the influence these views had on future nosological systems, the apparently purely picturesque episode corresponds to a landmark in the history of psychiatry.
Kleine-Levin syndrome misdiagnosed as schizophrenia
Authors: Bonnet F , Thibaut F , Levillain D , Petit M
Published: July 2002

A 27 year-old man initially considered as a schizophrenic patient was later diagnosed as having Kleine-Levin syndrome.
Kinetic and spectroscopic characterization of native and metal‐substituted β‐lactamase from Aeromonas hydrophila AE036
Authors: Hernandez Valladares Maria , Kiefer Martin , Heinz Uwe , Paul Soto Raquel , Meyer-Klaucke Wolfram , Nolting Hans Friederich , Zeppezauer Michael , Galleni Moreno , Frère Jean-Marie , Rossolini Gian Maria , Amicosante Gianfranco , Adolph Hans-Werner
Published: July 2002

Two metal ion binding sites are conserved in metallo‐β‐lactamase from Aeromonas hydrophila. The ligands of a first zinc ion bound with picomolar dissociation constant were identified by EXAFS spectroscopy as one Cys, two His and one additional N/O donor. Sulfur‐to‐metal charge transfer bands are observed for all mono‐ and di‐metal species substituted with Cu(II) or Co(II) due to ligation of the single conserved cysteine residue. Binding of a second metal ion results in non‐competitive inhibition which might be explained by an alternative kinetic mechanism. A possible partition of metal ions between the two binding sites is discussed.
High‐molecular‐weight kininogen is a binding protein for tissue prokallikrein
Authors: Raab Armin , Kemme Michael
Published: July 2002

Human tissue prokallikrein, a zymogen of the kallikrein‐kinin system, circulates in plasma bound to neutrophils. Because plasma kininogens contribute to the assembly of kinin‐generating components on blood cells, these proteins were assessed for their ability to complex the kallikrein precursor. Using ligand blot and direct binding assays, biotinylated prokallikrein was found to bind only to high‐molecular‐weight kininogen and not to the low‐molecular‐weight form. The interaction was specific, reversible, and saturable yielding an estimated dissociation constant K
D=690 nM and a 1:1 stoichiometry. Specific kininogen binding of tissue prokallikrein also occurred at physiological plasma protein concentrations. These results provide the first evidence for a novel function of high‐molecular‐weight kininogen as a binding protein for tissue prokallikrein that could serve to localize the kallikrein precursor on the neutrophil surface.
Fine architecture of bacterial inclusion bodies
Authors: Carrió M.Mar , Cubarsi Rafael , Villaverde Antonio
Published: July 2002

The molecular organisation of protein aggregates, formed under physiological conditions, has been explored by in vitro trypsin treatment and electron microscopy analysis of bacterially produced inclusion bodies (IBs). The kinetic modelling of protein digestion has revealed variable proteolysis rates during protease exposure that are not compatible with a surface‐restricted erosion of body particles but with a hyper‐surfaced disintegration by selective enzymatic attack. In addition, differently resistant species of the IB proteins coexist within the particles, with half‐lives that differ among them up to 50‐fold. During in vivo protein incorporation throughout IB growth, a progressive increase of proteolytic resistance in all these species is observed, indicative of folding transitions and dynamic reorganisations of the body structure. Both the heterogeneity of the folding state and the time‐dependent folding transitions undergone by the aggregated polypeptides indicate that IBs are not mere deposits of collapsed, inert molecules but plastic reservoirs of misfolded proteins that would allow, at least up to a certain extent, their in vivo recovery and transference to the soluble cell fraction.
Efp as a primary estrogen‐responsive gene in human breast cancer
Authors: Ikeda Kazuhiro , Orimo Akira , Higashi Yasuhiro , Muramatsu Masami , Inoue Satoshi
Published: July 2002

We have previously isolated the efp (estrogen‐responsive finger protein) that is required for the normal estrogen‐induced cell proliferation. Here, we show the genomic organization of the human efp gene which consists of nine exons. The efp mRNA was expressed in human breast tumors and the estrogen‐induced expression of the efp was found in MCF‐7 human breast cancer cells. Moreover, efp promoter activity was enhanced through the estrogen‐responsive element dependent on estrogen and estrogen receptor. These results suggest that the efp can mediate estrogen actions such as cell growth in human breast cancer as a primary responsive gene.
Cleavage and phosphorylation of XRCC4 protein induced by X‐irradiation
Authors: Matsumoto Yoshihisa , Suzuki Norio , Namba Naoki , Umeda Noriko , Ma Xue-Jun , Morita Akinori , Tomita Masanori , Enomoto Atsushi , Serizawa Shinobu , Hirano Kazuya , Sakai Kazuo , Yasuda Hideyo , Hosoi Yoshio
Published: July 2002

We report the p35 and p60 forms of XRCC4 protein, appearing in human leukemia MOLT‐4 or U937 cells following X‐irradiation or hyperthermia. p35 appeared in conjunction with the cleavage of DNA‐dependent protein kinase catalytic subunit (DNA‐PKcs) and the fragmentation of internucleosomal DNA, and was suppressed by Ac‐DEVD‐CHO. p35 was also produced in vitro by treating MOLT‐4 cell lysate with recombinant caspases, suggesting that p35 was a caspase‐cleaved fragment of XRCC4 in apoptotic cell death. p60 was sensitive to treatment with phosphatase or wortmannin and was undetectable in M059J cells deficient in DNA‐PKcs. However, p60 was found in ataxia‐telangiectasia cells after irradiation. These results indicated p60 as a phosphorylated form of XRCC4, requiring DNA‐PKcs but not ataxia‐telangiectasia mutated (ATM).
Ca2+‐reversible inhibition of the mitochondrial megachannel by ubiquinone analogues
Authors: Martinucci Silvia , Szabò Ildikò , Tombola Francesco , Zoratti Mario
Published: July 2002

Ubiquinone 0 and decylubiquinone have been reported to inhibit the mitochondrial permeability transition pore (PTP) [Fontaine, E., Ichas, F. and Bernardi, P. (1998) J. Biol. Chem. 273, 25734–25740], offering a new clue to its molecular composition. In patch‐clamp experiments on rat liver mitochondria we have observed that these compounds also inhibit the previously described mitochondrial megachannel (MMC), confirming its identification as the PTP. Inhibition can be reversed by increasing [Ca2+], in analogy to the behavior observed with several other disparate PTP/MMC inhibitors. To rationalize the ability of Ca2+ to overcome inhibition by various quite different compounds we propose that it acts via the phospholipid bilayer.
Self‐complementary motifs (SCM) in α‐crystallin small heat shock proteins
Authors: Farnsworth Patricia N. , Singh Kamalendra
Published: July 2002

Small heat shock proteins (sHsp) have been implicated in many cell processes involving the dynamics of protein–protein interactions. Two unusual sequences containing self‐complementary motifs (SCM) have been identified within the conserved α‐crystallin domain of sHsps. When two SCMs are aligned in an anti‐parallel direction (N to C and C to N), the charged or polar residues form either salt bridges or hydrogen bonds while the non‐polar residues participate in hydrophobic interactions. When aligned in reverse order, the residues of these motifs in α‐crystallin subunits form either hydrophobic and/or polar interactions. Homology based molecular modeling of the C‐terminal domain of α‐crystallin subunits using the crystal structure of MjHSP16.5 suggests that SCM1 and 2 participate in stabilizing secondary structure and subunit interactions. Also there is overwhelming evidence that these motifs are important in the chaperone‐like activity of α‐crystallin subunits. These sequences are conserved and appear to be characteristic of the entire sHsp superfamily. Similar motifs are also present in the Hsp70 family and the immunoglobulin superfamily.
A CDE/CHR tandem element regulates cell cycle‐dependent repression of cyclin B2 transcription
Authors: Lange-zu Dohna Christine , Brandeis Michael , Berr Frieder , Mössner Joachim , Engeland Kurt
Published: July 2002

Cyclin B is an important regulator of progression through the cell division cycle. The oscillating appearance of cyclin B1 and B2 proteins during the cell cycle is in part due to fluctuating mRNA levels. We had identified earlier a tandem promoter element named cell cycle‐dependent element (CDE) and cell cycle genes homology region (CHR) which regulates cell cycle‐dependent transcription of cdc25C, cyclin A and cdc2. Here we describe that cyclin B2 transcription is repressed through a novel CDE/CHR element in resting and G1 cells. By relief of this repression in S and G2 oscillating expression of cyclin B2 mRNA is achieved during the cell cycle.
The glucocorticoid receptor and STAT6 physically and functionally interact in T‐lymphocytes
Authors: Biola Armelle , Andréau Karine , David Muriel , Sturm Marie , Haake Markus , Bertoglio Jacques , Pallardy Marc
Published: July 2002

In lymphocytes, glucocorticoids (GC)‐ and interleukin‐4‐signaling pathways are known to interact, as evidenced by inhibition of IL‐4‐mediated proliferation by dexamethasone or suppression of GC‐induced apoptosis by IL‐4. In this study, we characterized the molecular basis for this reciprocal interference. We report that, in murine CTLL‐2 cells, IL‐4 inhibits GC‐induced MMTV (mouse mammary tumor virus) promoter transactivation, and that GC suppress IL‐4‐induced transactivation of a STAT6 (signal transducers and activators of transcription 6)‐responsive promoter without affecting IL‐4‐stimulated STAT6 DNA‐binding. Moreover, we evidenced a physical association between GC receptor and STAT6, which proved to be functionally relevant, since STAT6 overexpression increased the IL‐4 inhibitory effect on GC‐induced MMTV transactivation.
Mutation in the NDUFS4 gene of complex I abolishes cAMP‐dependent activation of the complex in a child with fatal neurological syndrome
Authors: Papa Sergio , Scacco Salvatore , Sardanelli Anna Maria , Vergari Rosaria , Papa Francesco , Budde Sandy , van den Heuvel Lambert , Smeitink Jan
Published: July 2002

Evidence is presented showing that in a patient with fatal neurological syndrome, the homozygous 5 bp duplication in the cDNA of the NDUFS4 18 kDa subunit of complex I abolishes cAMP‐dependent phosphorylation of this protein and activation of the complex. These findings show for the first time that human complex I is regulated via phosphorylation of the subunit encoded by the NDUFS4 gene.
Identification of gcpE as a novel gene of the 2‐C‐methyl‐D‐erythritol 4‐phosphate pathway for isoprenoid biosynthesis in Escherichia coli
Authors: Campos Narciso , Rodrı́guez-Concepción Manuel , Seemann Myriam , Rohmer Michel , Boronat Albert
Published: July 2002

The 2‐C‐methyl‐D‐erythritol 4‐phosphate (MEP) pathway for isoprenoid biosynthesis is essential in most eubacteria and plants and has remarkable biotechnological interest. However, only the first steps of this pathway have been determined. Using bioinformatic and genetic approaches, we have identified gcpE as a novel gene of the MEP pathway. The distribution of this gene in bacteria and plants strictly parallels that of the gene encoding 1‐deoxy‐D‐xylulose 5‐phosphate reductoisomerase, which catalyses the first committed step of the MEP pathway. Our data demonstrate that the gcpE gene is essential for the MEP pathway in Escherichia coli and indicate that this gene is required for the trunk line of the isoprenoid biosynthetic route.
Essential role of the N‐terminal autoregulatory sequence in the regulation of phenylalanine hydroxylase
Authors: Jennings Ian G. , Teh Trazel , Kobe Bostjan
Published: July 2002

Phenylalanine hydroxylase (PAH) is activated by its substrate phenylalanine and inhibited by its cofactor tetrahydrobiopterin (BH4). The crystal structure of PAH revealed that the N‐terminal sequence of the enzyme (residues 19–29) partially covered the enzyme active site, and suggested its involvement in regulation. We show that the protein lacking this N‐terminal sequence does not require activation by phenylalanine, shows an altered structural response to phenylalanine, and is not inhibited by BH4. Our data support the model where the N‐terminal sequence of PAH acts as an intrasteric autoregulatory sequence, responsible for transmitting the effect of phenylalanine activation to the active site.
Making decisions through Myc
Authors: Nasi Sergio , Ciarapica Roberta , Jucker Richard , Rosati Jessica , Soucek Laura
Published: July 2002

c‐Myc is a transcriptional regulator involved in carcinogenesis through its role in growth control and cell cycle progression. Here we attempt to relate its role in stimulating the G1–S transition to the ability to affect functioning of key cell cycle regulators, and we focus on how its property of modulating transcription of a wide range of target genes could explain its capacity to affect multiple pathways leading to proliferation, apoptosis, growth, and transformation.
A new face on apoptosis: death‐associated protein 3 and PDCD9 are mitochondrial ribosomal proteins
Authors: Koc Emine Cavdar , Ranasinghe Asoka , Burkhart William , Blackburn Kevin , Koc Hasan , Moseley Arthur , Spremulli Linda L.
Published: July 2002

Two proteins known to be involved in promoting apoptosis in mammalian cells have been identified as components of the mammalian mitochondrial ribosome. Proteolytic digestion of whole mitochondrial ribosomal subunits followed by analysis of the peptides present using liquid chromatography–tandem mass spectrometry revealed that the proapoptotic proteins, death‐associated protein 3 (DAP3) and the programmed cell death protein 9, are both components of the mitochondrial ribosome. DAP3 has motifs characteristic of guanine nucleotide binding proteins and is probably the protein that accounts for the nucleotide binding activity of mammalian mitochondrial ribosomes. The observations reported here implicate mitochondrial protein synthesis as a major component in cellular apoptotic signaling pathways.
Dual Ser and Thr phosphorylation of CPI‐17, an inhibitor of myosin phosphatase, by MYPT‐associated kinase
Authors: MacDonald Justin A. , Eto Masumi , Borman Meredith A. , Brautigan David L. , Haystead Timothy A.J.
Published: July 2002

Phosphorylation of CPI‐17 and PHI‐1 by the MYPT1‐associated kinase (M110 kinase) was investigated. M110 kinase is a recently identified serine/threonine kinase with a catalytic domain that is homologous to that of ZIP kinase (ZIPK. GST‐rN‐ZIPK, a constitutively active GST fusion fragment, phosphorylates CPI‐17 (but not PHI‐1) to a stoichiometry of 1.7 mol/mol. Phosphoamino acid analysis revealed phosphorylation of both Ser and Thr residues. Phosphorylation sites in CPI‐17 were identified as Thr 38 and Ser 12 using Edman sequencing with32P release and a point mutant of Thr 38.
The induction of apoptosis in proliferating human fibroblasts by oxygen radicals is associated with a p53‐ and p21WAF1CIP1 induction
Authors: Gansauge Susanne , Gansauge Frank , Gause Heike , Poch Bertram , Schoenberg Michael H , Beger Hans G
Published: July 2002

© 1997 Federation of European Biochemical Societies.
Engineering of diffraction‐quality crystals of the NF‐κB P52 homodimer:DNA complex
Authors: Cramer Patrick , Müller Christoph W
Published: July 2002

© 1997 Federation of European Biochemical Societies.
The effects of pH on the oxidation of low‐density lipoprotein by copper and metmyoglobin are different
Authors: Rodrı́guez-Malaver Antonio J. , Leake David S. , Rice-Evans Catherine A.
Published: July 2002

The amplification of low‐density lipoprotein (LDL) peroxidation in vitro by copper and myoglobin are well‐studied biochemical approaches for investigating the oxidative modification of LDL and its role in the pathogenesis of atherosclerosis. Since the acidity of the environment is increased in inflammatory sites, the aim of this study was to investigate the effects of acidic pH on the oxidisability of LDL mediated by the haem protein myoglobin in comparison with that of copper‐mediated LDL oxidation. The results show that acidic pH enhances myoglobin‐mediated LDL oxidation as measured by conjugated dienes, lipid hydroperoxides and electrophoretic mobility, whilst a retardation is observed with copper as pro‐oxidant; the mechanism probably relates to the effects of pH on the decomposition and formation of lipid hydroperoxides and the relative influences of copper ions and of myoglobin under these conditions.
Identification of a novel nuclear localization signal in Sam68
Authors: Ishidate Takao , Yoshihara Satoshi , Kawasaki Yoshihiro , Roy Badal Chandra , Toyoshima Kumao , Akiyama Tetsu
Published: July 2002

Sam68, a nuclear RNA binding protein, binds to Src and is phosphorylated at tyrosine residues in an M‐phase specific manner. Here we identified a stretch of 24 amino acid residues in the COOH‐terminal portion of Sam68 which function as a nuclear localization signal. This signal sequence bears no apparent homology to any other known nuclear localization sequence. However, this sequence was found to contain a motif, PPXXR (P, Pro; R, Arg), which is conserved in various RNA binding proteins including hnRNP proteins. Replacement of Arg in this motif with Ala abolished the nuclear accumulation of a GFP fusion protein, suggesting that this residue is important in translocating the protein to the nucleus.
A mutant form of the ribosomal protein L1 reveals conformational flexibility
Authors: Unge J , Al-Karadaghi S , Liljas A , Jonsson B.-H , Eliseikina I , Ossina N , Nevskaya N , Fomenkova N , Garber M , Nikonov S
Published: July 2002

The crystal structure of the mutant S179C of the ribosomal protein L1 from Thermus thermophilus has been determined at 1.9 Å resolution. The mutant molecule displays a small but significant opening of the cavity between the two domains. The domain movement seems to be facilitated by the flexibility of at least two conserved glycines. These glycines may be necessary for the larger conformational change needed for an induced fit mechanism upon binding RNA. The domain movement makes a disulfide bridge possible between the incorporated cysteines in two monomers of the mutant L1.
Restriction of intramolecular movements within the Cry1Aa toxin molecule of Bacillus thuringiensis through disulfide bond engineering
Authors: Schwartz Jean-Louis , Juteau Marc , Grochulski Pawel , Cygler Miroslaw , Préfontaine Gabrielle , Brousseau Roland , Masson Luke
Published: July 2002

Disulfide bridges were introduced into Cry1Aa, a Bacillus thuringiensis lepidopteran toxin, to stabilize different protein domains including domain I α‐helical regions thought to be involved in membrane integration and permeation. Bridged mutants could not form functional ion channels in lipid bilayers in the oxidized state, but upon reduction with β‐mercaptoethanol, regained parental toxin channel activity. Our results show that unfolding of the protein around a hinge region linking domain I and II is a necessary step for pore formation. They also suggest that membrane insertion of the hydrophobic hairpin made of α‐helices 4 and 5 in domain I plays a critical role in the formation of a functional pore.