Score = 87.4 bits (215), Expect = 2e-17, Method: Compositional matrix adjust.
Identities = 41/93 (44%), Positives = 63/93 (67%), Gaps = 2/93 (2%)
Query: 7 VIPTLKQCMSIERAQMRVRVEVSAGVKDVKKLKEKLVKCATSVENEEWSGGGLLLICLID 66
IP L++ + IERA+M++RV + K+ K + KL + VE ++W G L ++ LI+
Sbjct: 159 AIPKLRETLKIERAKMKIRVAIPT--KEAKSVHTKLKTLFSDVEVDDWQDGSLEMVGLIE 216
Query: 67 PGKYREIDELVRTETRGQGTLELLNLKEVTEGE 99
PG +R +D+LVR ET+G G LE+L+LK+V EGE
Sbjct: 217 PGSFRALDDLVRNETKGHGRLEILSLKDVVEGE 249
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of ribosome maturation factors from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation. Caenorhabditis elegans (taxid: 6239)
>sp|Q86KZ5|SBDS_DICDI Ribosome maturation protein SBDS OS=Dictyostelium discoideum GN=sbds PE=3 SV=2
Required for the assembly of mature ribosomes and ribosome biogenesis. Triggers the GTP-dependent release of ribosome maturation factors from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Dictyostelium discoideum (taxid: 44689)
>sp|Q5ZIY4|SBDS_CHICK Ribosome maturation protein SBDS OS=Gallus gallus GN=SBDS PE=2 SV=1
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Gallus gallus (taxid: 9031)
>sp|Q6DIT8|SBDS_XENTR Ribosome maturation protein SBDS OS=Xenopus tropicalis GN=sbds PE=2 SV=1
Score = 79.3 bits (194), Expect = 6e-15, Method: Compositional matrix adjust.
Identities = 48/97 (49%), Positives = 63/97 (64%), Gaps = 3/97 (3%)
Query: 7 VIPTLKQCMSIERAQMRVRVEVSAGVKDVKKLKEKLVKCATSVENEEWSGGGLLLICLID 66
VI LK+ M IERA MR+R + A K K K + T EN + L ++CLID
Sbjct: 157 VIKQLKETMQIERAHMRLRFILPAKDGKKLKEKLKPLIKHTESENFDQE---LEIVCLID 213
Query: 67 PGKYREIDELVRTETRGQGTLELLNLKEVTEGEEVLE 103
PG +REIDEL+R ET+G+GTLE+L+LK+V EG+E E
Sbjct: 214 PGCFREIDELIRCETKGKGTLEVLSLKDVEEGDEKFE 250
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of eif6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating eif6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Xenopus tropicalis (taxid: 8364)
>sp|A5D8M6|SBDS_XENLA Ribosome maturation protein SBDS OS=Xenopus laevis GN=sbds PE=2 SV=1
Score = 78.6 bits (192), Expect = 1e-14, Method: Compositional matrix adjust.
Identities = 48/97 (49%), Positives = 62/97 (63%), Gaps = 3/97 (3%)
Query: 7 VIPTLKQCMSIERAQMRVRVEVSAGVKDVKKLKEKLVKCATSVENEEWSGGGLLLICLID 66
VI LK+ M IERA MR+R V A K K K + EN + L ++CLID
Sbjct: 157 VIKQLKETMQIERAHMRLRFIVPAKDGKKLKEKLKPLIKHIESENFDQE---LEIVCLID 213
Query: 67 PGKYREIDELVRTETRGQGTLELLNLKEVTEGEEVLE 103
PG +REIDEL+R ET+G+GTLE+L+LK+V EG+E E
Sbjct: 214 PGCFREIDELIRCETKGKGTLEVLSLKDVEEGDEKFE 250
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of eif6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating eif6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Xenopus laevis (taxid: 8355)
>sp|Q5RAZ2|SBDS_PONAB Ribosome maturation protein SBDS OS=Pongo abelii GN=SBDS PE=2 SV=1
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Pongo abelii (taxid: 9601)
>sp|Q9Y3A5|SBDS_HUMAN Ribosome maturation protein SBDS OS=Homo sapiens GN=SBDS PE=1 SV=4
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Homo sapiens (taxid: 9606)
>sp|Q5RK30|SBDS_RAT Ribosome maturation protein SBDS OS=Rattus norvegicus GN=Sbds PE=2 SV=1
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Rattus norvegicus (taxid: 10116)
>sp|P70122|SBDS_MOUSE Ribosome maturation protein SBDS OS=Mus musculus GN=Sbds PE=1 SV=4
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Mus musculus (taxid: 10090)
>sp|Q3SWZ6|SBDS_BOVIN Ribosome maturation protein SBDS OS=Bos taurus GN=SBDS PE=2 SV=1
Required for the assembly of mature ribosomes and ribosome biogenesis. Together with EFTUD1, triggers the GTP-dependent release of EIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating EIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation.
Bos taurus (taxid: 9913)
Close Homologs in the Non-Redundant Database Detected by BLAST
Score = 70.4 bits (173), Expect = 3e-17
Identities = 42/77 (54%), Positives = 51/77 (66%), Gaps = 5/77 (6%)
Query: 7 VIPTL--KQCMSIERAQMRVRVEVSAGVKDVKKLKEKLVK-CATSVENEEWSGGGLLLIC 63
VI L KQ + I RA+MRVRV V VK KK+KEKL K VE EE SGGG L+
Sbjct: 52 VIKKLQEKQIIPIARAKMRVRVTVP--VKAAKKVKEKLKKLYEFKVEEEEESGGGWELVV 109
Query: 64 LIDPGKYREIDELVRTE 80
LI+PG +RE+DEL++ E
Sbjct: 110 LIEPGLFRELDELLKKE 126
This family is highly conserved in species ranging from archaea to vertebrates and plants. The family contains several Shwachman-Bodian-Diamond syndrome (SBDS) proteins from both mouse and humans. Shwachman-Diamond syndrome is an autosomal recessive disorder with clinical features that include pancreatic exocrine insufficiency, haematological dysfunction and skeletal abnormalities. Members of this family play a role in RNA metabolism. Length = 126
This protein family, possibly universal in both archaea and eukaryotes, appears to be involved in (ribosomal) RNA metabolism. Mutations in the human ortholog are associated with Shwachman-Bodian-Diamond syndrome.
>PF09377 SBDS_C: SBDS protein C-terminal domain; InterPro: IPR018978 This entry represents the C-terminal domain of proteins that are highly conserved in species ranging from archaea to vertebrates and plants []
Probab=99.91 E-value=1.1e-24 Score=150.70 Aligned_cols=77 Identities=45% Similarity=0.660 Sum_probs=70.7
Q ss_pred ccHhHHHHhhhh--hcCccceeeEEEEEEeeCcchHHHHHHHHHhhcccceeeeeeCCeEEEEEEeCCCChHHHHHHHhh
Q psy1332 2 YYYSQVIPTLKQ--CMSIERAQMRVRVEVSAGVKDVKKLKEKLVKCATSVENEEWSGGGLLLICLIDPGKYREIDELVRT 79 (103)
Q Consensus 2 ~QalevIk~Lk~--~iPI~RA~Mrl~v~~~ip~~~~~~~~~~l~~~~~~ie~e~~~~~~~~~v~~I~Pg~~r~i~~lv~~ 79 (103)
+|||++||+|++ +|||+||+|+++|+ +|.++++++++.|.+++..+++++|++|+|+++|+||||+||+|++++++
T Consensus 47 ~QalevIk~L~~~~~ipI~ra~m~l~v~--ip~~~~~~~~~~l~~~~~~i~~~~~~~~~~~~~~~i~pg~~r~l~~~v~~ 124 (125)
T PF09377_consen 47 QQALEVIKKLKEKQIIPIKRAKMRLRVT--IPSKYAKKVKDKLLKLGAKIEEEEQNDGSWEMVFLIDPGLYRELDELVNK 124 (125)
T ss_dssp HHHHHHHHHHTT--TS--EEEEEEEEEE--EBCCCHHHHHHHHHHHSEEEEEEEETTSCEEEEEEEEGGGHHHHHHHHHH
T ss_pred HHHHHHHHHHHHhCCCceeeeeEEEEEE--eCHHHHHHHHHHHHHhhcEeeecccCCCeEEEEEEECCcchHHHHHHHcc
Confidence 599999999998 99999999999999 99999999999999999877666667999999999999999999999998
Q ss_pred h
Q psy1332 80 E 80 (103)
Q Consensus 80 ~ 80 (103)
|
T Consensus 125 e 125 (125)
T PF09377_consen 125 E 125 (125)
T ss_dssp H
T ss_pred C
Confidence 5
The family contains several Shwachman-Bodian-Diamond syndrome (SBDS, OMIM 260400) proteins from both mouse and humans. Shwachman-Diamond syndrome is an autosomal recessive disorder with clinical features that include pancreatic exocrine insufficiency, haematological dysfunction and skeletal abnormalities. It is characterised by bone marrow failure and leukemia predisposition. Members of this family play a role in RNA metabolism [, ]. In yeast Sdo1 is involved in the biogenesis of the 60S ribosomal subunit and translational activation of ribosomes. Together with the EF-2-like GTPase RIA1 (EfI1), it triggers the GTP-dependent release of TIF6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating TIF6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. This data links defective late 60S subunit maturation to an inherited bone marrow failure syndrome associated with leukemia predisposition []. A number of uncharacterised hydrophilic proteins of about 30 kDa share regions of similarity. These include, Mouse protein 22A3. Saccharomyces cerevisiae chromosome XII hypothetical protein YLR022c. Caenorhabditis elegans hypothetical protein W06E11.4. Methanocaldococcus jannaschii (Methanococcus jannaschii) hypothetical protein MJ0592. ; GO: 0042254 ribosome biogenesis; PDB: 2KDO_A 2L9N_A 2WBM_B 1P9Q_C 1T95_A.
Eukaryotic cells harbor 2 protein synthesis systems: one localized in the cytoplasm, the other in the mitochondria. Most factors regulating mitochondrial protein synthesis are encoded by nuclear genes, translated in the cytoplasm, and then transported to the mitochondria. The eukaryotic system of elongation factor (EF) components is more complex than that in prokaryotes, with both cytoplasmic and mitochondrial elongation factors and multiple isoforms being expressed in certain species. Eukaryotic EF-2 operates in the cytosolic protein synthesis machinery of eukaryotes, EF-Gs in protein synthesis in bacteria. Eukaryotic mtEFG1 proteins show significant homology to bacterial EF-Gs. Mutants in yeast mtEFG1 have impaired mitochondrial protein synthesis, respiratory defects and a tendency to lose mitochondrial DNA. There are two forms of mtEFG present in mammals (desig
>PF00679 EFG_C: Elongation factor G C-terminus; InterPro: IPR000640 Translation elongation factors are responsible for two main processes during protein synthesis on the ribosome [, , ]
EF1A (or EF-Tu) is responsible for the selection and binding of the cognate aminoacyl-tRNA to the A-site (acceptor site) of the ribosome. EF2 (or EF-G) is responsible for the translocation of the peptidyl-tRNA from the A-site to the P-site (peptidyl-tRNA site) of the ribosome, thereby freeing the A-site for the next aminoacyl-tRNA to bind. Elongation factors are responsible for achieving accuracy of translation and both EF1A and EF2 are remarkably conserved throughout evolution. Elongation factor EF2 (EF-G) is a G-protein. It brings about the translocation of peptidyl-tRNA and mRNA through a ratchet-like mechanism: the binding of GTP-EF2 to the ribosome causes a counter-clockwise rotation in the small ribosomal subunit; the hydrolysis of GTP to GDP by EF2 and the subsequent release of EF2 causes a clockwise rotation of the small subunit back to the starting position [, ]. This twisting action destabilises tRNA-ribosome interactions, freeing the tRNA to translocate along the ribosome upon GTP-hydrolysis by EF2. EF2 binding also affects the entry and exit channel openings for the mRNA, widening it when bound to enable the mRNA to translocate along the ribosome. This entry represents the C-terminal domain found in EF2 (or EF-G) of both prokaryotes and eukaryotes (also known as eEF2), as well as in some tetracycline-resistance proteins. This domain adopts a ferredoxin-like fold consisting of an alpha/beta sandwich with anti-parallel beta-sheets. It resembles the topology of domain III found in these elongation factors, with which it forms the C-terminal block, but these two domains cannot be superimposed []. This domain is often found associated with (IPR000795 from INTERPRO), which contains the signatures for the N terminus of the proteins. More information about these proteins can be found at Protein of the Month: Elongation Factors [].; GO: 0005525 GTP binding; PDB: 1WDT_A 2DY1_A 3CB4_F 3DEG_C 2EFG_A 1ELO_A 2XSY_Y 2WRK_Y 1DAR_A 2WRI_Y ....
>cd03710 BipA_TypA_C BipA_TypA_C: a C-terminal portion of BipA or TypA having homology to the C terminal domains of the elongation factors EF-G and EF-2
A member of the ribosome binding GTPase superfamily, BipA is widely distributed in bacteria and plants. BipA is a highly conserved protein with global regulatory properties in Escherichia coli. BipA is phosphorylated on a tyrosine residue under some cellular conditions. Mutants show altered regulation of some pathways. BipA functions as a translation factor that is required specifically for the expression of the transcriptional modulator Fis. BipA binds to ribosomes at a site that coincides with that of EF-G and has a GTPase activity that is sensitive to high GDP:GTP ratios and, is stimulated by 70S ribosomes programmed with mRNA and aminoacylated tRNAs. The growth rate-dependent induction of BipA allows the efficient expression of Fis, thereby modulating a range of downstream processes, including DNA metabolism and type III secreti
>cd03713 EFG_mtEFG_C EFG_mtEFG_C: domains similar to the C-terminal domain of the bacterial translational elongation factor (EF) EF-G
Included in this group is the C-terminus of mitochondrial Elongation factor G1 (mtEFG1) and G2 (mtEFG2) proteins. Eukaryotic cells harbor 2 protein synthesis systems: one localized in the cytoplasm, the other in the mitochondria. Most factors regulating mitochondrial protein synthesis are encoded by nuclear genes, translated in the cytoplasm, and then transported to the mitochondria. The eukaryotic system of elongation factor (EF) components is more complex than that in prokaryotes, with both cytoplasmic and mitochondrial elongation factors and multiple isoforms being expressed in certain species. During the process of peptide synthesis and tRNA site changes, the ribosome is moved along the mRNA a distance equal to one codon with the addition of each amino acid. In bacteria this translocation step is catalyzed by EF-G_GTP, which is hydrolyzed to provide
>cd01514 Elongation_Factor_C Elongation factor G C-terminus
This domain includes the carboxyl terminal regions of elongation factors (EFs) bacterial EF-G, eukaryotic and archeal EF-2 and eukaryotic mitochondrial mtEFG1s and mtEFG2s. This group also includes proteins similar to the ribosomal protection proteins Tet(M) and Tet(O), BipA, LepA and, spliceosomal proteins: human 116kD U5 small nuclear ribonucleoprotein (snRNP) protein (U5-116 kD) and yeast counterpart Snu114p. This domain adopts a ferredoxin-like fold consisting of an alpha-beta sandwich with anti-parallel beta-sheets, resembling the topology of domain III found in the elongation factors EF-G and eukaryotic EF-2, with which it forms the C-terminal block. The two domains however are not superimposable and domain III lacks some of the characteristics of this domain. EF-2/EF-G in complex with GTP, promotes the translocation step of translation. During translocation the peptidyl-tRNA is moved from the A site to the P site, the
>cd04096 eEF2_snRNP_like_C eEF2_snRNP_like_C: this family represents a C-terminal domain of eukaryotic elongation factor 2 (eEF-2) and a homologous domain of the spliceosomal human 116kD U5 small nuclear ribonucleoprotein (snRNP) protein (U5-116 kD) and, its yeast counterpart Snu114p
Yeast Snu114p is essential for cell viability and for splicing in vivo. U5-116 kD binds GTP. Experiments suggest that GTP binding and probably GTP hydrolysis is important for the function of the U5-116 kD/Snu114p. In complex with GTP, EF-2 promotes the translocation step of translation. During translocation the peptidyl-tRNA is moved from the A site to the P site, the uncharged tRNA from the P site to the E-site and, the mRNA is shifted one codon relative to the ribosome.
>cd03711 Tet_C Tet_C: C-terminus of ribosomal protection proteins Tet(M) and Tet(O)
This domain has homology to the C terminal domains of the elongation factors EF-G and EF-2. Tet(M) and Tet(O) catalyze the release of tetracycline (Tc) from the ribosome in a GTP-dependent manner thereby mediating Tc resistance. Tcs are broad-spectrum antibiotics. Typical Tcs bind to the ribosome and inhibit the elongation phase of protein synthesis, by inhibiting the occupation of site A by aminoacyl-tRNA.
>PF09186 DUF1949: Domain of unknown function (DUF1949); InterPro: IPR015269 Members of this entry are a set of functionally uncharacterised hypothetical bacterial proteins
They adopt a ferredoxin-like fold, with a beta-alpha-beta-beta-alpha-beta arrangement []. This entry contains the protein Impact, which is a translational regulator that ensures constant high levels of translation under amino acid starvation. It acts by interacting with Gcn1/Gcn1L1, thereby preventing activation of Gcn2 protein kinases (EIF2AK1 to 4) and subsequent down-regulation of protein synthesis. It is evolutionary conserved from eukaryotes to archaea []. ; PDB: 2CVE_A 1VI7_A.
>cd04098 eEF2_C_snRNP eEF2_C_snRNP: This family includes a C-terminal portion of the spliceosomal human 116kD U5 small nuclear ribonucleoprotein (snRNP) protein (U5-116 kD) and, its yeast counterpart Snu114p
This domain is homologous to the C-terminal domain of the eukaryotic translational elongation factor EF-2. Yeast Snu114p is essential for cell viability and for splicing in vivo. U5-116 kD binds GTP. Experiments suggest that GTP binding and probably GTP hydrolysis is important for the function of the U5-116 kD/Snu114p. In complex with GTP, EF-2 promotes the translocation step of translation. During translocation the peptidyl-tRNA is moved from the A site to the P site, the uncharged tRNA from the P site to the E-site and, the mRNA is shifted one codon relative to the ribosome.
>cd03709 lepA_C lepA_C: This family represents the C-terminal region of LepA, a GTP-binding protein localized in the cytoplasmic membrane
LepA is ubiquitous in Bacteria and Eukaryota (e.g. Saccharomyces cerevisiae GUF1p), but is missing from Archaea. LepA exhibits significant homology to elongation factors (EFs) Tu and G. The function(s) of the proteins in this family are unknown. The N-terminal domain of LepA is homologous to a domain of similar size found in initiation factor 2 (IF2), and in EF-Tu and EF-G (factors required for translation in Escherichia coli). Two types of phylogenetic tree, rooted by other GTP-binding proteins, suggest that eukaryotic homologs (including S. cerevisiae GUF1) originated within the bacterial LepA family. LepA has never been observed in archaea, and eukaryl LepA is organellar. LepA is therefore a true bacterial GTPase, found only in the bacterial lineage.
This domain includes the carboxyl terminal regions of Elongation factor G, elongation factor 2 and some tetracycline resistance proteins and adopt a ferredoxin-like fold.
>TIGR00257 IMPACT_YIGZ uncharacterized protein, YigZ family
This uncharacterized protein family includes YigZ, which has been crystallized, from E. coli. YigZ is homologous to the protein product of the mouse IMPACT gene. Crystallography shows a two-domain stucture, and the C-terminal domain is suggested to bind nucleic acids. The function is unknown. Note that the ortholog from E. coli was shown fused to the pepQ gene in GenBank entry X54687. This caused occasional misidentification of this protein as pepQ; this family is found in a number of species that lack pepQ.
LepA (GUF1 in Saccaromyces) is a GTP-binding membrane protein related to EF-G and EF-Tu. Two types of phylogenetic tree, rooted by other GTP-binding proteins, suggest that eukaryotic homologs (including GUF1 of yeast) originated within the bacterial LepA family. The function is unknown.
This bacterial (and Arabidopsis) protein, termed TypA or BipA, a GTP-binding protein, is phosphorylated on a tyrosine residue under some cellular conditions. Mutants show altered regulation of some pathways, but the precise function is unknown.
After peptide bond formation, this elongation factor of bacteria and organelles catalyzes the translocation of the tRNA-mRNA complex, with its attached nascent polypeptide chain, from the A-site to the P-site of the ribosome. Every completed bacterial genome has at least one copy, but some species have additional EF-G-like proteins. The closest homolog to canonical (e.g. E. coli) EF-G in the spirochetes clusters as if it is derived from mitochondrial forms, while a more distant second copy is also present. Synechocystis PCC6803 has a few proteins more closely related to EF-G than to any other characterized protein. Two of these resemble E. coli EF-G more closely than does the best match from the spirochetes; it may be that both function as authentic EF-G.
This model represents archaeal elongation factor 2, a protein more similar to eukaryotic EF-2 than to bacterial EF-G, both in sequence similarity and in sharing with eukaryotes the property of having a diphthamide (modified His) residue at a conserved position. The diphthamide can be ADP-ribosylated by diphtheria toxin in the presence of NAD.
