Enzyme Nomenclature

Continued from EC 3.6.4

EC 3.6.5 Acting on GTP; involved in cellular and subcellular movement

Contents

EC 3.6.5.1 heterotrimeric G-protein GTPase
EC 3.6.5.2 small monomeric GTPase
EC 3.6.5.3 protein-synthesizing GTPase
EC 3.6.5.4 signal-recognition-particle GTPase
EC 3.6.5.5 dynamin GTPase
EC 3.6.5.6 tubulin GTPase


Entries

EC 3.6.5.1

Accepted name: heterotrimeric G-protein GTPase

Reaction: GTP + H2O = GDP + phosphate

Systematic name: GTP phosphohydrolase (signalling)

Comments: This group comprises GTP-hydrolysing systems, where GTP and GDP alternate in binding. This group includes stimulatory and inhibitory G-proteins such as Gs, Gi, Go and Golf, targetting adenylate cyclase and/or K+ and Ca2+ channels; Gq stimulating phospholipase C; transducin activating cGMP phosphodiesterase; gustducin activating cAMP phosphodiesterase. Golf is instrumental in odour perception, transducin in vision and gustducin in taste recognition. At least 16 different α subunits (39-52 kDa), 5 β subunits (36 kDa) and 12 γ subunits (6-9 kDa) are known.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Neer, E.J. Heterotrimeric G proteins: organizers of transmembrane signals. Cell 80 (1995) 249-259. [PMID: 7834744]

2. Sprang, S.R. G protein mechanisms: insights from structural analysis. Annu. Rev. Biochem. 66 (1997) 639-678. [PMID: 9242920]

3. Bondarenko, V.A., Deasi, M., Dua, S., Yamazaki, M., Amin, R.H., Yousif, K.K., Kinumi, T., Ohashi, M., Komori, N., Matsumoto, H., Jackson, K.W., Hayashi, F., Usukura, J., Lipikin, V.M. and Yamazaki, A. Residues within the polycationic region of cGMP phosphodiesterase γ subunit crucial for the interaction with transducin α subunit. Identification by endogenous ADP-ribosylation and site-directed mutagenesis. J. Biol. Chem. 272 (1997) 15856-15864. [PMID: 9188484]

4. Ming, D., Ruiz-Avila, L. and Margolskee, R.F. Characterization and solubilization of bitter-responsive receptors that couple to gustducin. Proc. Natl. Acad. Sci. USA 95 (1998) 8933-8938. [PMID: 9671782]

[EC 3.6.5.1 created 2000 as EC 3.6.1.46, transferred 2003 to EC 3.6.5.1]

EC 3.6.5.2

Accepted name: small monomeric GTPase

Reaction: GTP + H2O = GDP + phosphate

Systematic name: GTP phosphohydrolase (cell-regulating)

Comments: A family of about 50 enzymes with a molecular mass of 21 kDa that are distantly related to the α-subunit of heterotrimeric G-protein GTPase (EC 3.6.5.1). They are involved in cell-growth regulation (Ras subfamily), membrane vesicle traffic and uncoating (Rab and ARF subfamilies), nuclear protein import (Ran subfamily) and organization of the cytoskeleton (Rho and Rac subfamilies).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Bourne, H.R., Sanders, D.A. and McCormick, F. The GTPase superfamily: conserved structure and molecular mechanisms. Nature 349 (1991) 117-127. [PMID: 1898771]

2. Hall, A. Small GTP-binding proteins and the regulation of actin cytoskeleton. Annu. Rev. Cell Biol. 10 (1994) 31-54. [PMID: 7888179]

3. Geyer, M. and Wittinghofer, A. GEFs, GAPs, GDIs and effectors: taking a closer (3D) look at the regulation of Ras-related GTP-binding proteins. Curr. Opin. Struct. Biol. 7 (1997) 786-792. [PMID: 9434896]

4. Vitale, N., Moss, J. and Vaughan, M. Molecular characterization of the GTPase-activating domain of ADP-ribosylation factor domain protein 1 (ARD1). J. Biol. Chem. 273 (1998) 2553-2560. [PMID: 9446556]

[EC 3.6.5.2 created 2000 as EC 3.6.1.47, transferred 2003 to EC 3.6.5.2]

EC 3.6.5.3

Accepted name: protein-synthesizing GTPase

Reaction: GTP + H2O = GDP + phosphate

Other name(s): elongation factor (EF); initiation factor (IF); peptide-release or termination factor

Systematic name: GTP phosphohydrolase (mRNA-translation-assisting)

Comments: This enzyme comprises a family of proteins involved in prokaryotic as well as eukaryotic protein synthesis. In the initiation factor complex, it is IF-2b (98 kDa) that binds GTP and subsequently hydrolyses it in prokaryotes. In eukaryotes, it is eIF-2 (150 kDa) that binds GTP. In the elongation phase, the GTP-hydrolysing proteins are the EF-Tu polypeptide of the prokaryotic transfer factor (43 kDa), the eukaryotic elongation factor EF-1α (53 kDa), the prokaryotic EF-G (77 kDa), the eukaryotic EF-2 (70-110 kDa) and the signal recognition particle that play a role in endoplasmic reticulum protein synthesis (325 kDa). EF-Tu and EF-1α catalyse binding of aminoacyl-tRNA to the ribosomal A-site, while EF-G and EF-2 catalyse the translocation of peptidyl-tRNA from the A-site to the P-site. GTPase activity is also involved in polypeptide release from the ribosome with the aid of the pRFs and eRFs.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Kurzchalia, T.V., Bommer, U.A., Babkina, G.T. and Karpova, G.G. GTP interacts with the γ-subunit of eukaryotic initiation factor EIF-2. FEBS Lett. 175 (1984) 313-316. [PMID: 6566615]

2. Kisselev, L.L. and Frolova, L.Yu. Termination of translation in eukaryotes. Biochem. Cell Biol. 73 (1995) 1079-1086. [PMID: 8722024]

3. Rodnina, M.V., Savelsberg, A., Katunin, V.I. and Wintermeyer, W. Hydrolysis of GTP by elongation factor G drives tRNA movement on the ribosome. Nature 385 (1997) 37-41. [PMID: 8985244]

4. Freistroffer, D.V., Pavlov, M.Y., MacDougall, J., Buckingham, R.H. and Ehrenberg, M. Release factor RF3 in E. coli accelerates the dissociation of release factors RF1 and RF2 from the ribosome in a GTP-dependent manner. EMBO J. 16 (1997) 4126-4133. [PMID: 9233821]

5. Krab, I.M. and Parmeggiani, A. EF-Tu, a GTPase odyssey. Biochim. Biophys. Acta 1443, (1998) 1-22. [PMID: 9838020]

[EC 3.6.5.3 created 2000 as EC 3.6.1.48, transferred 2003 to EC 3.6.5.3]

EC 3.6.5.4

Accepted name: signal-recognition-particle GTPase

Reaction: GTP + H2O = GDP + phosphate

Systematic name: GTP phosphohydrolase (protein-synthesis-assisting)

Comments: Activity is associated with the signal-recognition particle (a protein- and RNA-containing structure involved in endoplasmic-reticulum-associated protein synthesis).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Connolly, T. and Gilmore, R. The signal recognition particle receptor mediates the GTP-dependent displacement of SRP from the signal sequence of the nascent polypeptide. Cell 57 (1989) 599-610. [PMID: 2541918]

2. Connolly, T., Rapiejko, P.J. and Gilmore, R. Requirement of GTP hydrolysis for dissociation of the signal recognition particle from its receptor. Science 252 (1991) 1171-1173. [PMID: 1851576]

3. Miller, J.D., Wilhelm, H., Gierasch, L., Gilmore, R. and Walter, P. GTP binding and hydrolysis by the signal recognition particle during initiation of protein translocation. Nature 366 (1993) 351-354. [PMID: 8247130]

4. Freymann, D.M., Keenan, R.J., Stroud, R.M. and Walter, P. Structure of the conserved GTPase domain of the signal recognition particle. Nature 385 (1997) 361-364. [PMID: 9002524]

[EC 3.6.5.4 created 2000 as EC 3.6.1.49, transferred 2003 to EC 3.6.5.4]

EC 3.6.5.5

Accepted name: dynamin GTPase

Reaction: GTP + H2O = GDP + phosphate

Systematic name: GTP phosphohydrolase (vesicle-releasing)

Comments: An enzyme with a molecular mass of about 100 kDa that is involved in endocytosis and is instrumental in pinching off membrane vesicles.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Warnock, D.E. and Schmid, S.L. Dynamin GTPase, a force-generating molecular switch. Bioessays 18 (1996) 885-893. [PMID: 8939066]

2. McClure, S.J. and Robinson, P.J. Dynamin, endocytosis and intracellular signalling. Mol. Membr. Biol. 13 (1996) 189-215. [PMID: 9116759]

3. Oh, P., McIntosh, D.P. and Schnitzer, J.E. Dynamin at the neck of caveolae mediates their budding to form transport vesicles by GTP-driven fission from the plasma membrane of endothelium. J. Cell Biol. 141 (1998) 101-114. [PMID: 9531551]

[EC 3.6.5.5 created 2000 as EC 3.6.1.50, transferred 2003 to EC 3.6.5.5]

EC 3.6.5.6

Accepted name: tubulin GTPase

Reaction: GTP + H2O = GDP + phosphate

Systematic name: GTP phosphohydrolase (microtubule-releasing)

Comments: An intrinsic activity of α-tubulin involved in tubulin folding, division plane formation in prokaryotic cells and others.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Yu, X.C. and Margolin, W. Ca2+-mediated GTP-dependent dynamic assembly of bacetrial cell division protein FtsZ into asters and polymer networks in vitro. EMBO J. 16, (1997) 5455-5463. [PMID: 9312004]

2. Tian, G., Bhamidipati, A., Cowan, N.J . and Lewis, S.A. Tubulin folding cofactors as GTPase-activating proteins. GTP hydrolysis and the assembly of the α/β-tubulin heterodimer. J. Biol. Chem. 274, (1999) 24054-24058. [PMID: 10446175]

3. Roychowdhury, S., Panda, D., Wilson, L. and Rasenick, M.M. G protein α subunits activate tubulin GTPase and modulate microtubule polymerization dynamics. J. Biol. Chem. 274, (1999) 13485-13490. [PMID: 10224115]

[EC 3.6.5.6 created 2000 as EC 3.6.1.51, transferred 2003 to EC 3.6.5.6]


Continued with EC 3.7 to EC 3.13
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