HMM Summary Page: TIGR01494

FunctionHAD ATPase, P-type, family IC
Trusted Cutoff62.30
Domain Trusted Cutoff62.30
Noise Cutoff29.20
Domain Noise Cutoff29.20
Isology Typesubfamily
EC Number3.6.3.-
HMM Length478
AuthorSelengut J
Entry DateApr 24 2002 10:12AM
Last ModifiedFeb 14 2011 3:27PM
CommentThe P-type ATPases are a large family of trans-membrane transporters acting on charged substances. The distinguishing feature of the family is the formation of a phosphorylated intermediate (aspartyl-phosphate) during the course of the reaction. Another common name for these enzymes is the E1-E2 ATPases based on the two isolable conformations: E1 (unphosphorylated) and E2 (phosphorylated). Generally, P-type ATPases consist of only a single subunit encompassing the ATPase and ion translocation pathway, however, in the case of the potassium (TIGR01497) and sodium/potassium (TIGR01106) varieties, these functions are split between two subunits[5]. Additional small regulatory or stabilizing subunits may also exist in some forms. P-type ATPases are nearly ubiquitous in life and are found in numerous copies in higher organisms (at least 45 in Arabidopsis thaliana, for instance [1]). Phylogenetic analyses have revealed that the P-type ATPase subfamily is divided up into groups based on substrate specificities [2] and this is represented in the various subfamily and equivalog models that have been made: IA (K+) TIGR01497, IB (heavy metals) TIGR01525, IIA1 (SERCA-type Ca++) TIGR01116, IIA2 (PMR1-type Ca++) TIGR01522, IIB (PMCA-type Ca++) TIGR01517, IIC (Na+/K+, H+/K+ antiporters) TIGR01106, IID (fungal-type Na+ and K+) TIGR01523, IIIA (H+) TIGR01647, IIIB (Mg++) TIGR01524, IV (phospholipid, flippase) TIGR01652 and V (unknown specificity) TIGR01657. The crystal structure of one calcium-pumping ATPase [4] and an analysis of the fold of the catalytic domain of the P-type ATPases [3] have been published. These reveal that the catalytic core of these enzymes is a haloacid dehalogenase(HAD)-type aspartate-nucleophile hydrolase. The location of the ATP-binding loop in between the first and second HAD conserved catalytic motifs defines these enzymes as members of subfamily I of the HAD superfamily (see also TIGR01493, TIGR01509, TIGR01549, TIGR01544 and TIGR01545). Based on these classifications, the P-type ATPase _superfamily_ corresponds to the IC subfamily of the HAD superfamily.
ReferencesRN [1] RM PMID: 11402198 RT Inventory of the Superfamily of P-type Ion Pumps in Arabidopsis. RA Axelsen KB, Palmgren MG. RL Plant Physiol. 2001 Jun; 126(2): 696-706. RN [2] RM PMID:9419228 RT Evolution of Substrate Specificities in the P-type ATPase Superfamily. RA Axelsen KB, Palmgren, MG. RL J Mol Evol. 1998 Jan; 46(1): 84-101. RN [3] RM PMID:9584613 RT The catalytic domain of the P-type ATPase has the haloacid dehalogenase fold. RA Aravind L, Galperin MY, Koonin EV. RL Trends Biochem Sci. 1998 Apr; 23(4): 127-9. RN [4] RM PMID: 10864315 RT Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 A resolution. RA Toyoshima C, Nakasako M, Nomura H, Ogawa H. RL Nature. 2000 Jun 8; 405(6787): 647-55 RN [5] RM PMID: 1970651 RT The bacterial Kdp K(+)-ATPase and its relation to other transport ATPases, such as the Na+/K(+)- and Ca2(+)-ATPases in higher organisms. RA Epstein W, Walderhaug MO, Polarek JW, Hesse JE, Dorus E, Daniel JM. RL Philos Trans R Soc Lond B Biol Sci 1990 Jan 30;326(1236):479-86; discussion 486-7 DR HAMAP; MF_00285; 77 of 78