title: Structural divergence between the two subgroups of P5 ATPases.
abstract: Evolution of P5 type ATPases marks the origin of eukaryotes but still they remain the least characterized pumps in the superfamily of P-type ATPases. Phylogenetic analysis of available sequences suggests that P5 ATPases should be divided into at least two subgroups, P5A and P5B. P5A ATPases have been identified in the endoplasmic reticulum and seem to have basic functions in protein maturation and secretion. P5B ATPases localize to vacuolar/lysosomal or apical membranes and in animals play a role in hereditary neuronal diseases. Here we have used a bioinformatical approach to identify differences in the primary sequences between the two subgroups. P5A and P5B ATPases appear have a very different membrane topology from other P-type ATPases with two and one, respectively, additional transmembrane segments inserted in the N-terminal end. Based on conservation of residues in the transmembrane region, the two P5 subgroups most likely have different substrate specificities although these cannot be predicted from their sequences. Furthermore, sequence differences between P5A and P5B ATPases are identified in the catalytic domains that could influence key kinetic properties differentially. Together these findings indicate that P5A and P5B ATPases are structurally and functionally different.
authors.affiliation: Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Plant Biology and Biotechnology, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
authors.forename: Danny Mollerup
authors.initials: DM
authors.lastname: Sørensen
authors.forename: Morten J
authors.initials: MJ
authors.lastname: Buch-Pedersen
authors.forename: Michael Gjedde
authors.initials: MG
authors.lastname: Palmgren
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000145:classification* / Q000235:genetics*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D019295:Computational Biology; D030562:Databases, Protein; D019143:Evolution, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000251:Adenosine Triphosphatases