|Function||HAD ATPase, P-type, family IC|
|Domain Trusted Cutoff||62.30|
|Domain Noise Cutoff||29.20|
|Entry Date||Apr 24 2002 10:12AM|
|Last Modified||Feb 14 2011 3:27PM|
|Comment||The 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. 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 ). Phylogenetic analyses have revealed that the P-type ATPase subfamily is divided up into groups based on substrate specificities  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  and an analysis of the fold of the catalytic domain of the P-type ATPases  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.|
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.
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.
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.
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
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|
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