bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calpactins: Calcium‐regulated membrane‐skeletal proteins
Authors: Glenney John R. 
Published: February 2005

AbstractThe calpactins are a novel group of proteins associated with the membrane skeleton. The two main forms, calpactin I and II, have been shown to bind to the cytoskeletal proteins actin and spectrin, as well as to anionic phospholipids, which may imply some sort of bridging role. By raising monoclonal antibodies to the heavy and light chains of calpactin I, and to calpactin II, the protein subunits were shown to be coordinately expressed, and the existence of separate calpactin pools hypothesized. Calcium‐binding studies suggest that the calpactins may translate Ca2+ signals into cellular responses at the membrane. Structural studies have revealed two distinct domains and are beginning to throw light on heavy‐‐light chain interaction and cytoskeletal attachment.
Permease on parade: Application of site‐directed mutagenesis to ion‐gradient driven active transport
Authors: Kaback H. Ronald 
Published: February 2005

AbstractOligonucleotide‐directed, site‐specific mutagenesis is being applied to the problem of ion‐gradient driven active transport with the lac permease as a model system. It has been shown that Arg‐302, His‐322 and Glu‐325, neighboring residues in putative transmembrane helices IX and X, play an important role in lactose‐coupled H+ translocation, possibly as components of a catalytic triad similar to that found in the serine proteases. In addition, Cys residues, long thought to be involved in the mechanism of the permease, are not directly involved in either substrate binding or H+ translocation. Finally, a variety of mutations have no effect on permease activity indicating that single amino acid changes do not lead indiscriminately to long‐range conformational alterations.
Gap junctions: Towards a molecular structure
Authors: Evans W. Howard 
Published: February 2005

AbstractGap junctions are ubiquitous plasma membrane specializations that allow cells to exchange small molecules and ions directly. The isolation, biochemical characterization and molecular cloning of the major protein of rat liver gap junctions lead to a clearer view of these membrane zones that allow cells to ‘talk’ to each other and co‐ordinate their activities in tissues and organs.
The pivotal role of ferritin in cellular iron homeostasis
Authors: Mattia Elena , van Renswoude Jos 
Published: February 2005

AbstractIron delivered by transferrin to the interior of the cell is in part utilized in biosynthetic processes and in part incorporated into ferritin, the major iron storage protein. The intracellular ferritin concentration is directly correlated to and determined by the extent of iron supply to the cell. Intracellular partitioning of iron to ferritin is suggested as forming the basis of cellular iron homeostasis.
Megabase methods: A quantum jump in recombinant DNA techniques
Authors: Jordan Bertrand R. 
Published: February 2005

AbstractUntil quite recently, recombinant DNA technology was not able to deal with DNA molecules larger than 20–40 kb. This is a serious limitation for the study of mammalian, and in particular human genomes whose total length is approx. 3 × 106 kb, since the best resolution of genetic and chromosomal analysis is usually the rough equivalent of 1000–5000 kb. Three recently developed methods promise to bridge this gap: pulsed field gel electrophoresis, which can analyze megabase‐sized DNA fragments; cloning in yeast, which can clone and propagate DNA fragments of several hundred kb; and jumping libraries, which allow ‘jumping’ over large distances along the chromosome. This review presents the current status of these very promising technologies.
DNA topoisomerases and DNA repair
Authors: Downes C. S. , Johnson R. T. 
Published: February 2005

AbstractDNA topoisomerases are enzymes that can modify, and may regulate, the topological state of DNA through concerted breaking and rejoining of the DNA strands. They have been believed to be directly involved in DNA excision repair, and perhaps to be required for the control of repair as well. The vicissitudes of this hypothesis provide a noteworthy example of the dangers of interpreting cellular phenomena without genetic information and vice versa.
Molecular and cellular biology of malaria
Authors: Braun Richard 
Published: February 2005

AbstractThanks to the extensive use of recombinant DNA technology and immunological methods, much insight into cellular functions of the human malaria parasite Plasmodium falciparum has been gained since it was learnt ten years ago how to grow this organism in culture. The amino acid sequence of over a dozen surface proteins of the parasite and of several proteins the parasite excretes into its most important host cell, the erythrocyte, have been determined. Interestingly many of these proteins show blocks of repeated amino acids. Several proteins have been shown to be involved in specific aspects of the complex hostparasite interaction, such as penetration of host cells or increased stickiness of infected red blood cells in the blood vessels. Some of the proteins described here may be protective antigens and may become important in vaccine development.
A new interleukin with pleiotropic activities
Authors: Kishimoto Tadamitsu , Hirano Toshio 
Published: February 2005

AbstractHuman B cell stimulatory factor 2 (originally designated BSF2) was initially characterized and isolated as a T cell‐derived factor that caused the terminal maturation of activated B cells to immunoglobulin producing cells. Molecular cloning of the cDNA has revealed that BSF2 is identical with 26 kD protein, interferon β2, plasmacytoma growth factor and hepatocyte stimulating factor and the designation “IL‐6” has been proposed for this molecule. It is now known that BSF2/IL‐6 has a wide variety of biological functions and that abnormal regulation of BSF2/IL‐6 expression may be related to the pathogenesis of certain autoimmune diseases such as rheumatoid arthritis and multiple myeloma.
Chromatin assembly in vitro and in vivo
Authors: Dilworth Stephen M. , Dingwall Colin 
Published: February 2005

AbstractThe assembly of nucleosomes and higher‐order chromatin structures has been extensively studied in vitro. Provided that non‐specific charge interactions are controlled, all the information for correct assembly is found to be inherent in the macromolecular components. Cellular extracts which can assemble chromatin in vitro with nucleosomes correctly spaced on the DNA have been studied in detail and also used to investigate the role of chromatin structure in transcription. However, the mechanisms of chromatin assembly in vivo are still controversial.
X chromosome inactivation: A hypothesis
Authors: McBurney Michael W. 
Published: February 2005

AbstractX‐chromosome inactivation refers to the coordinate regulation of almost all genes on the mammalian × chromosome. Most models for × chromosome inactivation suppose a role for methylation of × chromosome DNA sequences and/or the heterochromatinization of large «domains» of the × chromosome containing many genes.1 Some recent work concerning the expression of X‐linked transgenes, and parallels between regulated expression of sex‐linked genes in invertebrates and mammals, suggest that × chromosome inactivation may be a gene‐by‐gene event mediated by the interaction between regulatory sequences common to all X‐linked genes and soluble activators and repressors.
Biochemistry and physiology of nitrogen fixation
Authors: Haaker H. 
Published: February 2005

AbstractBiological dinitrogen fixation, the reduction of N2 to NH3, requires the enzyme nitrogenase, MgATP, a strongly reducing electron donor and an anaerobic environment. Reducing power for nitrogen fixation is generated by two particular mechanisms, while the mechanisms for protecting nitrogen fixation from oxygen show a greater diversity. Both the reduction and the protection aspects of nitrogen fixation, especially those of the legume root nodule, will be discussed.
Research opportunities in typhoid fever: Epidemiology and molecular biology
Authors: Calva Edmundo , Puente Jose Luis , Calva Juan José 
Published: February 2005

AbstractIt is estimated that typhoid fever (TF) annually affects more than 12 million persons, worldwide. TF is the result of a generalized infection by the enterobacterium Salmonella typhi. Patients with TF, most of whom live in developing countries have impaired activity for several weeks resulting in an important loss in productivity and welfare. Death may occur, with the single most frequent cause being intestinal perforation. While the first priority must be to develop better methods of disease prevention, there is also an urgent need to devise easy, accurate, and inexpensive diagnostic assays that will allow early routine distinction of TF from other febrile illnesses. Research on TF offers the opportunity to explore many aspects of pathogenesis and the host immune response, as well as to contribute toward the development of new vaccines and diagnostic laboratory tests.
Human endogenous retroviruses
Authors: Cohen Maurice , Larsson Erik 
Published: February 2005

AbstractSeveral studies have revealed the presence in human DNA of thousands of endogenous retrovirus genomes, or HERVs. Many HERVs are related to extant retroviruses that infect other vertebrates and some have been present in the germ line of primates for millions of years. Although the HERVs that have been isolated are defective and thus do not encode infectious retroviruses, there may be HERVs that are capable of infection. In addition, because HERVs are so ancient in the human lineage, evolution of the human genome may have included the acquisition of some HERV genes for strictly cellular functions.
Selectivity in solute transport: Binding sites and channel structure in maltoporin and other bacterial sugar transport proteins
Authors: Ferenci Thomas 
Published: February 2005

AbstractA stereospecific binding site is not the only determinant governing the selectivity of transport proteins. An understanding of transport across cellular membranes requires a description of the different compartments within a transmembrane channel; evidence for the existence of these compartments comes from the selectivity properties of genetically modified maltoporin. Such compartments may also be of significance in determining the specificity of other transport proteins.
Atrial natriuretic peptides: Receptors and second messengers
Authors: Waldman Scott A. , Murad Ferid 
Published: February 2005

AbstractAtrial natriuretic peptides appear to elicit their actions in some target tissues by binding to a novel cell‐surface transmembrane protein which possesses both peptide binding and guanylate cyclase activities. Ligand binding stimulates enzyme activity to produce increased intracellular concentrations of cyclic GMP which, in turn, mediates the cell's physiological response.
The chemical kinetics of molecular evolution
Authors: Woolley Paul 
Published: February 2005

AbstractThis article describes a current view of the events that initiated the transition from the rich organic and inorganic chemistry of the primitive Earth to the earliest forms of life. It is a personal condensation of the basic ideas developed in the so‐called Göttingen school. Most of these will be found in the seminal paper of Eigen1 and the other sources cited. A detailed exposition is given by Küppers2.
The acetylcholine receptor: Its molecular biology and biotechnological prospects
Authors: Changeux Jean‐Pierre 
Published: February 2005

AbstractThe structure and behaviour of the acetylcholine receptor (AChR) is described, and the evidence that it is an allosteric protein is discussed. The genes for the AChR subunits are subject to a complex set of spatio‐temporal transcriptional controls during development of the motor endplate, and these findings are reviewed here. Finally, the biotechnological prospects suggested by the new data are noted.
The structural and functional interrelationships of muscarinic acetylcholine receptor subtypes
Authors: Ramachandran J. , Peralta E. G. , Ashkenazi A. , Winslow J. W. , Capon D. J. 
Published: February 2005

AbstractMolecular cloning of the genes encoding the muscarinic acetylcholine receptors has shwon that receptor subtypes classified on the basis of pharmacological properties are related polypeptides encoded by distinct genes. These studies have laso revealed the existence of novel muscarinic receptor subtypes. Functional analysis of each of the subtypes expressed in mammalian cells indicates that the different subtypes activate distinct biochemical pathways, a finding that explains the tissue‐specific physiological response elicited by the neurotransmitter, acetylcholine.
The polyprotein nature of substance P precursors
Authors: Krause James E. , Macdonald Margaret R. , Takeda Yasuo 
Published: February 2005

AbstractSubstance P and related tachykinin peptides probably act as neurotransmitters or modulators of neurotransmission, and regulate biological processes as diverse as salivary secretion and transmission of pain signals. Substance P peptide sequences are expressed in three distinct mRNAs that are generated from one gene by differential RNA splicing. In addition to substance P, as many as three other tachykinin peptides can be generated from the polyprotein precursors by differential posttranslational processing. Three tachykinin receptor subtypes have been extensively characterized which differentially interact with the naturally occurring tachykinin peptides. Therefore, the generation of diversity of tachykinin peptides results from differential precursor RNA splicing and differential posttranslational processing. The specificity of peptide responses is the result of selective receptor subtype expression.
The genetic analysis of mitosis in Aspergillus nidulans
Authors: Ronald Morris N. , Doonan John H. , Osmani Stephen A. , Engle Dorothy B. 
Published: February 2005

AbstractWe describe here recent work on the molecular genetics of mitosis in the filamentous fungus Aspergillus nidulans. Aspergillus is one of three simple eukaryotes with powerful genetic systems that have been used to analyze mitosis. The modern molecular biological techniques available with this organism have made it possible to use mutations to identify genes and proteins that play an important role in mitosis. Three Aspergillus genes that affect mitosis are described. One gene, nimA, is specifically expressed late in the cell cycle and codes for a putative protein kinase that induces mitosis, even in cells blocked in S‐phase. The second gene, bimG, codes for a putative phosphatase that interacts functionally with the nimA kinase. The third gene, bimE, codes for a protein that suppresses mitosis during interphase, apparently by keeping nimA turned off. None of these genes appear to be similar to any of the genes affecting mitosis that have been characterized in other eukaryotes, but rather appear to be elements of a system that prevents mitosis from occurring during interphase.
The mechanism of anaphase spindle elongation
Authors: Cande W. Z. , Hogan C. J. 
Published: February 2005

AbstractAt anaphase chromosomes move to the spindle poles (anaphase A) and the spindle poles move apart (anaphase B). In vitro studies using isolated diatom spindles demonstrate that the primary mechano‐chemical event responsible for spindle elongation is the sliding apart of half‐spindle microtubules. Further, these forces are generated within the zone of microtubule overlap in the spindle midzone.
Regulation of meiosis: From DNA binding protein to protein kinase
Authors: McLeod Maureen 
Published: February 2005

AbstractThe transition from mitotic cell division to meiosis in yeast is governed by both the mating‐type genes and signals from the environment. Analysis of mutants that are unable to regulate entry into meiosis has identified many genes that function in this process and in some cases, the biochemical activity of their protein products has been described. At least two of the the mating‐type genes of Saccharomyces cerevisiae encode DNA binding proteins that regulate transcription of unlinked genes required for entry into meiosis. Meiotic development of the distantly related yeast, Schizosaccharomyces pombe, is also controlled by the mating‐type genes but in this yeast, their role is to regulate expression of a protein that acts as an inhibitor of a protein kinase. The ability to use the powerful tool of genetics in yeast has provided us with many new insights into the problem of meiotic development.
Insect baculoviruses: Powerful gene expression vectors
Authors: Miller Lois K. 
Published: February 2005

AbstractBaculovirus vectors have proven useful in producing high levels of biologically active eukaryotic proteins and providing cellular fractions which are enriched in the protein of interest. Expression occurs in infected insect cells which also provide a suitable environment for posttranslational modification and folding of the protein product. Stable baculovirus vectors can be constructed rapidly with a minimum of viral manipulation.
How does a key fit a flexible lock? Structure and dynamics in receptor function
Authors: Neubig Richard R. , Thomsen William J. 
Published: February 2005

AbstractThe preceding five years have brought remarkable advances in our understanding of the primary structure of drug receptors. The roles of certain amino acid residues in binding drugs and effecting receptor function have been proposed. As even more detailed structures become available, the goal of rational design of drug molecules based on predicted fits between the drug and its receptor will be near at hand. Although none of the classical receptors has yet yielded to X‐ray crystallographic analysis, the methods of molecular biology facilitate the production of the large amounts of these rare proteins necessary for crystallization. Receptor proteins share one fundamental characteristic with allosterically regulated enzymes. Both have the structural flexibility that allows information to be transmitted to distant parts of the molecule. We will discuss recent observations about receptor structure and the dynamic nature of drug receptors, and pose questions about the significance of receptor dynamics for drug design.
Regulation of pituitary peptides by the immune system
Authors: Hall Nicholas R. S. , O'Grady Maureen P. 
Published: February 2005

AbstractIt has long been thought that the central nervous system is able to influence the progression of disease. Furthermore, there is now overwhelming evidence that the communication pathways are bidirectional. A variety of immune system peptides are now known to be capable of transmitting information from the immune system to the central nervous system. These immunotransmitters include interleukins, interferons and thymosine peptides which have the capability of modulating slow‐wave sleep as well as the release of neuro‐ and pituitary peptides. In some instances, release of these peptides during early development may have long lasting, if not permanent effects upon the normal development of neuro‐endocrine circuits. Collectively these various brain mediated events appear to contribute in various and diverse ways to defense against pathogens. It is becoming more and more apparent that certain abnormalities within the immune system may be the consequence of a neurological abnormality. The converse is also true.
Trichothiodystrophy and the relationship between DNA repair and cancer
Authors: Lehmann A. R. 
Published: February 2005

AbstractThe identification of cellular deficiences in the ability to repair damage in DNA in individuals with several cancer‐prone genetic disorders, has led to the idea that defective DNA repair results in cancer. In patients with trichothiodystrophy, however, a recently discovered defect in the repair of ultraviolet damage in DNA is not associated with cancer‐proneness. Thus our previous ideas about the connections between DNA repair capacity and cancer susceptibility need to be reevaluated.
Proto‐oncogenes in cell differentiation
Authors: Zelenka Peggy S. 
Published: February 2005

AbstractProto‐oncogene products may be multi‐functional proteins with various roles in cell differentiation as well as cell proliferation. The molecular biology of the gene products of three well characterized proto‐oncogenes (c‐fos, c‐myc and c‐src) are described, and the roles of three other proto‐oncogene products, involved in hormone and growth factor reception, are reviewed.
Problems and paradigms: On the clonal origin of tumours – lessons from studies of intestinal epithelium
Authors: Schmidt Günter H. , Mead Roger 
Published: February 2005

AbstractClonal studies of adult chimaeric mouse epithelium have demonstrated the monoclonal composition of crypts of Lieberkühn(1). In neonatal life, however, polyclonal crypts have been found, indicating that crypts are of polyclonal origin(2). We here relate these findings to studies of mosaic tissues which have addressed the question whether solid tumours are of monoclonal or polyclonal origin (ref. 3 for review, 4). The issues has so far remained unresolved because the expected frequencies of polyclonal tumours, given polyclonal origins, have not previously been estimated. A general approach for the calculation of such expected values is suggested. The consistent reports of tumours with polyclonal components suggest that autocrine or paracrine mechanisms play an important role during tumorigenesis.
The emerging structure of the Agrobacterium T‐DNA transfer complex
Authors: Howard Elizabeth , Citovsky Vitaly 
Published: February 2005

AbstractSingle‐stranded DNA‐protein complex (T‐complex) is proposed to mediate T‐DNA transfer from Agrobacterium to plant cells. A novel model for transfer is presented which incorporates features of both bacterial conjugation and viral infection. Specific protein components of the T‐complex, its ultrastructure and possible functions in the plant cell are discussed.
Growth‐related protein kinases
Authors: Ralph Ray K. , Darkin‐Rattray Sandra , Schofield Phillip 
Published: February 2005

AbstractA protein kinase cascade is involved in the action of some mitogens. The cascade begins with receptor tyrosine kinase activation by growth factors. The resulting signal is transmitted into cells via phospholipid metabolism which produces a variety of second messengers and by intracellular protein kinase activation. The signal is then propagated and disseminated via a network of other proteln kinases and protein phosphatases. Recent research suggests that ribosomal protein S6 kinase and casein kinase II are two important elements in the kinase cascade that leads to the initiation of growth. The nature and some properties of these hitherto lesser known enzymes is considered.
Eukaryotic transcription factors
Authors: Polyanovsky Oleg L. , Stepchenko Alexander G. 
Published: February 2005

AbstractMany nuclear proteins have been found recently to interact with short conserved sequences which are involved in regulating the transcription of various genes. Nuclear transcription factors may be arbitrarily subdivided into two groups, ubiquitous and tissue‐specific. The transcription of one gene is usually regulated by several factors which interact with different sequences located either in the promoter region of the gene or outside it. The appearance or disappearance of transcription factors for some genes corresponds to certain phases of cell differentiation or dedifferentiation and even to individual stages of the cell cycle.