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- *****************************************
- * ATP/GTP-binding site motif A (P-loop) *
- *****************************************
-
- From sequence comparisons and crystallographic data analysis it has been shown
- [1,2,3,4,5] that an appreciable proportion of proteins that bind ATP or GTP
- share a number of more or less conserved sequence motifs. The best conserved
- of these motifs is a glycine-rich region, which probably forms a flexible loop
- between a beta-strand and an alpha-helix. This loop interacts with one of the
- phosphate groups of the nucleotide. This sequence motif is generally referred
- to as the 'A' consensus sequence [1] or the 'P-loop' [5].
-
- There are numerous ATP- or GTP-binding proteins in which the P-loop is found.
- We list below a number of protein families for which the relevance of the
- presence of such motif has been noted:
-
- - ATP synthase alpha and beta subunits.
- - Myosin heavy chains.
- - Kinesin heavy chains and kinesin-like proteins.
- - Guanylate kinase.
- - Thymidine kinase.
- - Thymidylate kinase.
- - Shikimate kinase.
- - Nitrogenase iron protein family (nifH/frxC).
- - ATP-binding proteins involved in 'active transport' (ABC transporters) [6].
- - ATP-dependent helicases [7,8].
- - GTP-binding elongation factors (EF-Tu, EF-1alpha, EF-G, EF-2, etc.).
- - Ras family of proteins (Ras, Rho, Rab, Ral, Ypt1, SEC4, etc.).
- - ADP-ribosylation factors family.
- - Bacterial dnaA protein.
- - Bacterial recA protein.
- - Bacterial recF protein.
- - Guanine nucleotide-binding proteins alpha subunits (Gi, Gs, Gt, G0, etc.).
- - DNA mismatch repair proteins mutS family.
- - Bacterial type II secretion system protein E.
-
- Not all ATP- or GTP-binding proteins are picked-up by this motif. A number of
- proteins escape detection because the structure of their ATP-binding site is
- completely different from that of the P-loop. Examples of such proteins are
- the E1-E2 ATPases or the glycolytic kinases. In other ATP- or GTP-binding
- proteins the flexible loop exists in a slightly different form; this is the
- case for tubulins or protein kinases. A special mention must be reserved for
- adenylate kinase, in which there is a single deviation from the P-loop
- pattern: in the last position Gly is found instead of Ser or Thr.
-
- -Consensus pattern: [AG]-x(4)-G-K-[ST]
- -Sequences known to belong to this class detected by the pattern: a majority.
- -Other sequence(s) detected in SWISS-PROT: in addition to the proteins listed
- above, the 'A' motif is also found in a number of other proteins. Most of
- these proteins probably bind a nucleotide, but others are definitively not
- ATP- or GTP-binding (as for example chymotrypsin, or human ferritin light
- chain).
-
- -Expert(s) to contact by email: Koonin E.V.
- koonin@ncbi.nlm.nih.gov
-
- -Last update: June 1994 / Text revised.
-
- [ 1] Walker J.E., Saraste M., Runswick M.J., Gay N.J.
- EMBO J. 1:945-951(1982).
- [ 2] Moller W., Amons R.
- FEBS Lett. 186:1-7(1985).
- [ 3] Fry D.C., Kuby S.A., Mildvan A.S.
- Proc. Natl. Acad. Sci. U.S.A. 83:907-911(1986).
- [ 4] Dever T.E., Glynias M.J., Merrick W.C.
- Proc. Natl. Acad. Sci. U.S.A. 84:1814-1818(1987).
- [ 5] Saraste M., Sibbald P.R., Wittinghofer A.
- Trends Biochem. Sci. 15:430-434(1990).
- [ 6] Higgins C.F., Hyde S.C., Mimmack M.M., Gileadi U., Gill D.R.,
- Gallagher M.P.
- J. Bioenerg. Biomembr. 22:571-592(1990).
- [ 7] Hodgman T.C.
- Nature 333:22-23(1988) and Nature 333:578-578(1988) (Errata).
- [ 8] Linder P., Lasko P., Ashburner M., Leroy P., Nielsen P.J., Nishi K.,
- Schnier J., Slonimski P.P.
- Nature 337:121-122(1989).
-