title: A putative proton binding site of plasma membrane H(+)-ATPase identified through homology modelling.
abstract: We have used the 2.6 A structure of the rabbit sarcoplasmic reticulum Ca(2+)-ATPase isoform 1a, SERCA1a [Toyoshima, C., Nakasako, M., Nomura, H. and Ogawa, H. (2000) Nature 405, 647-655], to build models by homology modelling of two plasma membrane (PM) H(+)-ATPases, Arabidopsis thaliana AHA2 and Saccharomyces cerevisiae PMA1. We propose that in both yeast and plant PM H(+)-ATPases a strictly conserved aspartate in transmembrane segment (M)6 (D684(AHA2)/D730(PMA1)), and three backbone carbonyls in M4 (I282(AHA2)/I331(PMA1), G283(AHA2)/I332(PMA1) and I285(AHA2)/V334(PMA1)) comprise a binding site for H3O(+), suggesting a previously unknown mechanism for transport of protons. Comparison with the structure of the SERCA1a made it feasible to suggest a possible receptor region for the C-terminal auto-inhibitory domain extending from the phosphorylation and anchor domains into the transmembrane region.
authors: Centre for Crystallographic Studies, Department of Chemistry, University of Copenhagen, Denmark.
authors: J T
authors: JT
authors: Bukrinsky
authors: M J
authors: MJ
authors: Buch-Pedersen
authors: S
authors: S
authors: Larsen
authors: M G
authors: MG
authors: Palmgren
mesh_terms: D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D017494:Proton Pumps / Q000737:chemistry / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D011522:Protons; D011817:Rabbits; D029701:Saccharomyces cerevisiae Proteins
chemical_list: C434364:PMA2 protein, S cerevisiae; D017494:Proton Pumps; D011522:Protons; D029701:Saccharomyces cerevisiae Proteins; C092477:PMA1 protein, S cerevisiae; D006180:Proton-Translocating ATPases