SII-SWORD/CoKE huggingface dataset:
Large ribosomal subunit protein eL31, conserved site (Ribosomal_eL31_CS)
Type: Conserved_site

A number of eukaryotic and archaebacterial large subunit ribosomal proteins can be grouped on the basis of sequence similarities. These proteins have 87 to 128 amino-acid residues. This family consists of:

Yeast eL31A (also known as L34)

Archaeal L31

Plants L31

Mammalian L31

Ribosomal protein eL31, which is present in archaea and eukaryotes, binds the 23S rRNA and is one of six protein components encircling the polypeptide exit tunnel. It is a component of the eukaryotic 60S (large) ribosomal subunit, and the archaeal 50S (large) ribosomal subunit .

This entry represents a conserved region located in the central section.

Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites . About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.

Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome .
Ribosome-binding factor A, conserved site (Ribosome-bd_factorA_CS)
Type: Conserved_site

Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites . About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.

Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome .

Ribosome-binding factor A (gene rbfA) is a bacterial protein that associates with free 30S ribosomal subunits. It does not associate with 30S subunits that are part of 70S ribosomes or polysomes. It is essential for efficient processing of 16S rRNA. Ribosome-binding factor A is a protein of from 13 to 15 Kd which is found in most bacteria. A putative chloroplastic form seems to exist in plants.

This entry represents a conserved site located in the second half of the protein.
Proteinase inhibitor I16, Streptomyces subtilisin-type inhibitor, conserved site (Prot_inh_SSI_I16_CS)
Type: Conserved_site

The Streptomyces family of bacteria produce a number of proteinase inhibitors, which belong to MEROPS inhibitor family I16, clan IY. They are characterised by their strong activity towards subtilisin (MEROPS peptidase family S8,

) and are collectively known as Streptomyces subtilisin inhibitors (SSI). Some SSI also inhibit trypsin, chymotrypsin (MEROPS peptidase family S1,

) and griselysin (MEROPS peptidase family M4,

) . Mutation of the active site residue can influence inhibition specificity .

SSI is a homodimer, each monomer containing 2 anti-parallel β-sheets and 2 short α-helices. Protease binding induces the widening of a channel-like structure, in which hydrophobic side-chains are sandwiched between 2 lobes . Loss of the C-terminal tetrapeptide VFAF drastically reduces the inhibitory effect of the proteins when there is less than one molecule of inhibitor present per molecule of enzyme. This implies that the tetrapeptide is neccessary to maintain the correct 3D fold . Structural similarities between the primary and secondary contact loops of SSI, and the ovomucoid and pancreatic secretory trypsin inhibitor family suggest evolution of the 2 families from a common ancestor .

This entry represents a conserved site with two cysteines involved in a disulfide bond.
Ribosomal protein bL25, short-form (Ribosomal_bL25_short)
Type: Family

This entry models the short-form of the ribosomal bL25 protein, previously known as L25. The long-form has homology to the general stress protein Ctc of Bacillus subtilis, a mesophile, and ribosomal protein TL5 of Thermus thermophilus, a thermophile. Ribosomal protein L25 of Escherichia coli and Haemophilus influenzae appear to be orthologous but consist only of the N-terminal half of Ctc and TL5. Both short (L25-like) and full-length (CTC-like) members of this family bind the E-loop of bacterial 5S rRNA .
Large ribosomal subunit protein bL25/Gln-tRNA synthetase, N-terminal (Rbsml_bL25/Gln-tRNA_synth_N)
Type: Homologous_superfamily

This superfamily represents the N-terminal domain, which has a β-barrel structure.

The bacterial large ribosomal subunit protein bL25, previously known as ribosomal protein L25, is bound to 5S rRNA along with uL5 and uL18, forming a separate domain of the ribosome . The solution structure of protein bL25 uncomplexed with RNA shows two significantly disordered loops and a closed β-barrel domain with a complex topology that has significant structural similarities to the N-terminal domain of the Thermus thermophilus ribosomal protein TL5, to the general stress protein CTC, and to the C-terminal anticodon-binding domain of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) . GlnRS contains a duplication consisting of two L25-like β-barrels domains with the swapping of N-terminal strands.
Large ribosomal subunit protein bL25, beta domain (Ribosomal_bL25_b-dom)
Type: Domain

This entry represents a domain with a mainly β-strand structure found in the large ribosomal subunit protein bL25 and similar proteins predominantly found in bacteria.

The bacterial large ribosomal subunit protein bL25, previously known as ribosomal protein L25, is bound to 5S rRNA along with uL5 and uL18, forming a separate domain of the ribosome . The solution structure of protein bL25 uncomplexed with RNA shows two significantly disordered loops and a closed β-barrel domain with a complex topology that has significant structural similarities to the N-terminal domain of the Thermus thermophilus ribosomal protein TL5, to the general stress protein CTC, and to the C-terminal anticodon-binding domain of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) . GlnRS contains a duplication consisting of two L25-like β-barrels domains with the swapping of N-terminal strands.
Glutamyl/glutaminyl-tRNA synthetase, class Ib, catalytic domain (Glu/Gln-tRNA-synth_Ib_cat-dom)
Type: Domain

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction . These proteins differ widely in size and oligomeric state, and have limited sequence homology . The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric . Class II aminoacyl-tRNA synthetases share an anti-parallel β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. Based on their mode of binding to the tRNA acceptor stem, both classes of tRNA synthetases have been subdivided into three subclasses, designated 1a, 1b, 1c and 2a, 2b, 2c .

Glutamate-tRNA ligase (also known as glutamyl-tRNA synthetase;

) is a class I aminoacyl-tRNA synthetase. This enzyme shares similarities with glutaminyl-tRNA synthetase in terms of structure and catalytic properties. Glutamyl-tRNA synthetase (GluRS) and glutaminyl-tRNA synthetase (GlnRS) are grouped in the GlxRS subclass because of the shared evolutionary pathway of their catalytic domains. The catalytic domain of Glx subfamily is believed to be more ancient, having evolved from a common GluRS ancestor that contained only the catalytic domain. Anticodon binding domains of extant bacterial and eukaryotic/archeal GlxRS appeared independently at a later stage, with the anticodon-binding domain of bacterial GlnRS being acquired by an unique horizontal gene transfer event from the eukaryotic kingdom .

Bacterial GluRS are divided into two groups -discriminatory GluRS (D-GluRS) and non-discriminatory GluRS (ND-GluRS). While D-GluRS exclusively catalyses the transfer of Glu to tRNA(Glu), the ND-GluRS can also glutamylate tRNA(Gln) forming Glu-tRNAGln. The misacylated product is then transformed to Gln-tRNA(Gln) by an enzyme known as glutamyl-tRNA(Gln) amidotransferase. The bacterial GluRS structure consists of four domains. The N-terminal half (domains 1 and 2) contains the 'Rossman fold' typical for class I aminoacyl-tRNA synthetases and resembles the corresponding part of GlnRS, whereas the C-terminal half exhibits a GluRS-specific structural features .
Glutamyl/glutaminyl-tRNA synthetase, class Ib, anti-codon binding domain (Glu/Gln-tRNA-synth_Ib_codon-bd)
Type: Domain

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction . These proteins differ widely in size and oligomeric state, and have limited sequence homology . The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric . Class II aminoacyl-tRNA synthetases share an anti-parallel β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. Based on their mode of binding to the tRNA acceptor stem, both classes of tRNA synthetases have been subdivided into three subclasses, designated 1a, 1b, 1c and 2a, 2b, 2c .

Glutamate-tRNA ligase (also known as glutamyl-tRNA synthetase;

) is a class I aminoacyl-tRNA synthetase. This enzyme shares similarities with glutaminyl-tRNA synthetase in terms of structure and catalytic properties. Glutamyl-tRNA synthetase (GluRS) and glutaminyl-tRNA synthetase (GlnRS) are grouped in the GlxRS subclass because of the shared evolutionary pathway of their catalytic domains. The catalytic domain of Glx subfamily is believed to be more ancient, having evolved from a common GluRS ancestor that contained only the catalytic domain. Anticodon binding domains of extant bacterial and eukaryotic/archeal GlxRS appeared independently at a later stage, with the anticodon-binding domain of bacterial GlnRS being acquired by an unique horizontal gene transfer event from the eukaryotic kingdom .

Bacterial GluRS are divided into two groups -discriminatory GluRS (D-GluRS) and non-discriminatory GluRS (ND-GluRS). While D-GluRS exclusively catalyses the transfer of Glu to tRNA(Glu), the ND-GluRS can also glutamylate tRNA(Gln) forming Glu-tRNAGln. The misacylated product is then transformed to Gln-tRNA(Gln) by an enzyme known as glutamyl-tRNA(Gln) amidotransferase. The bacterial GluRS structure consists of four domains. The N-terminal half (domains 1 and 2) contains the 'Rossman fold' typical for class I aminoacyl-tRNA synthetases and resembles the corresponding part of GlnRS, whereas the C-terminal half exhibits a GluRS-specific structural features .
Nuclear transition protein 1, conserved site (Nuclear_transition_prot1_CS)
Type: Conserved_site

Nuclear transition protein 1 (TP1) is one of the spermatid-specific proteins . TP1 is a basic protein well conserved in mammalian species. In mammals, the second stage of spermatogenesis is characterised by the conversion of nucleosomal chromatin to the compact, non-nucleosomal and transcriptionally inactive form found in the sperm nucleus. This condensation is associated with a double-protein transition. The first transition corresponds to the replacement of histones by several spermatid-specific proteins (also called transition proteins) which are themselves replaced by protamines during the second transition.

This entry represents a heptapeptide located in positions 28 to 34, which contains five basic residues (Arg or Lys) as well as a tyrosine that could be essential for the destabilisation of chromatin by intercalating between the bases of DNA.
Bordetella pertussis toxin B, subunit 2/3, C-terminal (ToxinB_su2/3_C_BORPE)
Type: Domain

A large group of bacterial exotoxins are referred to as "A/B toxins", essentially because they are formed from two subunits . The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit .

Bordetella pertussis is the causative agent of whooping cough, and is a Gram-negative aerobic coccus. Its major virulence factor is the pertussis toxin, an A/B exotoxin that mediates both colonisation and toxaemic stages of the the disease . Recombinant, inactive forms of the 5 subunits that make up the toxin have proven to be good vaccines. The S2 and S3 subunits of the toxin form part of the "B" moiety. They are responsible for binding the whole toxin to host cells prior to invasion, and are classed as adhesins . S2 attaches to a host receptor called lactosylceramide. It has also been speculated that the S3 unit may preferentially bind phagocytes.

The crystal structure of pertussis toxin has been determined to 2.9A resolution . The catalytic A-subunit (S1) shares structural similarity with other ADP-ribosylating bacterial toxins, although differences in the C-terminal portion explain its unique activation mechanism. Despite its heterogeneous subunit composition, the structure of the cell-binding B-oligomer (S2, S3, two copies of S4, and S5) resembles the symmetrical B-pentamers of the cholera and shiga toxin families, but it interacts differently with the A-subunit and there is virtually no sequence similarity between B-subunits of the different toxins. Two peripheral domains that are unique to the pertussis toxin B-oligomer share structural similarity with a calcium-dependent eukaryotic lectin, and reveal possible receptor-binding sites.
Conjugal transfer protein TrbK (Conjugal_tfr_protein_TrbK)
Type: Family

Members of this family are encoded between the genes for TrbJ and TrbL of P-type plasmid conjugal transfer systems, and therefore are TrbK, a member of a guild of unrelated TrbK protein families. The similarly located TrbK of plasmid RP4 functions in entry exclusion, and the current family may as well, despite lacking any detectable homology. Members of this family include TrbK of the Ti plasmid from Agrobacterium, shown not to be required for transfer, which would be consistent with a role in entry exclusion rather than transfer itself. An entry exclusion function for TrbK of the Ti plasmid has been suggested . This small protein shares close C-terminal sequence homology to the much longer protein encoded by the neighbouring gene TrbJ.
Cortexin (Cortexin)
Type: Family

Cortexin is a neuron-specific, 82-residue membrane protein which is found especially in vertebrate brain cortex tissue. It may mediate extracellular or intracellular signalling of cortical neurons during forebrain development. Cortexin is present at significant levels in the foetal brain, suggesting that it may be important to neurons of both the developing and adult cerebral cortex. Cortexin has a conserved single membrane-spanning region in the middle of each sequence . In humans, there is selective expression of Cortexin 3 (CTXN3) in the kidney as well as the brain . This entry contains Cortexins 1, 2 and 3, and Cortexin domain-containing proteins.
Frizzled domain (Frizzled_dom)
Type: Domain

The frizzled (fz) domain is an extracellular domain of about 120 amino acids.It was first identified in the alpha-1 chain of type XVIII collagen and in members of the Frizzled family of seven transmembrane (7TM) proteins which act as receptors for secreted Wingless (Wg)/Wnt glycoproteins . In addition to these proteins, one or two copies of the fz domain are also found in:

The Frzb family; secreted frizzled-like proteins.

Smoothened; another 7TM receptor involved in hedgehog signaling.

Carboxpeptidase Z (CPZ).

Transmembrane serine protease corin (atrial natriuretic peptide-converting enzyme).

Two receptor tyrosine kinases (RTKs) subfamilies, the Ror family and the muscle-specific kinase (MuSK) family.

As the fz domain contains 10 cysteines which are largely conserved, it has also been called cysteine-rich domain (CRD) . The fz domain also contains several other highly conserved residues, for example, a basic amino acid follows C6, and a conserved proline residues lies four residues C-terminal to C9 . The crystal structure of a fz domain shows that it is predominantly α-helical with all cysteines forming disulphide bonds. In addition to helical regions, two short β-strands at the N terminus form a minimal β-sheet with the second β sheet passing through a knot created by disulphide bonds .

Several fz domains have been shown to be both necessary and sufficient for Wg/Wnt ligand binding, strongly suggesting that the fz domain is a Wg/Wnt interacting domain .
Large ribosomal subunit protein bL9, C-terminal (Ribosomal_bL9_C)
Type: Domain

This entry represents the large ribosomal subunit protein bL9. In Escherichia coli, bL9 is known to bind directly to the 23S rRNA. It belongs to a family of ribosomal proteins grouped on the basis of sequence similarities .

The crystal structure of Bacillus stearothermophilus bL9 shows the 149-residue protein comprises two globular domains connected by a rigid linker . Each domain contains an rRNA binding site, and the protein functions as a structural protein in the large subunit of the ribosome. The C-terminal domain consists of two loops, an α-helix and a three-stranded mixed parallel, anti-parallel β-sheet packed against the central α-helix. The long central α-helix is exposed to solvent in the middle and participates in the hydrophobic cores of the two domains at both ends.

Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites . About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.

Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome .