title: Characterization of PISP, a novel single-PDZ protein that binds to all plasma membrane Ca2+-ATPase b-splice variants.
abstract: Plasma membrane Ca(2+) ATPases (PMCAs) maintain intracellular Ca(2+) homeostasis and participate in the local regulation of Ca(2+) signaling. Spatially separate demands for Ca(2+) regulation require proper membrane targeting of PMCAs, but the mechanism of PMCA targeting is unknown. Using the PMCA2b carboxyl-terminal tail as yeast two-hybrid bait, we isolated a novel PDZ domain-containing protein from a human brain cDNA library. This protein, named PISP for PMCA-interacting single-PDZ protein, consists of 140 amino acids and contains little else besides a single PDZ domain. Pulldown experiments showed that PISP interacts with all PMCA b-splice forms. PISP was found to be ubiquitously expressed and, in MDCK cells, was present in a punctate pattern throughout the cytosol and at the basolateral membrane. When added to microsomal membranes expressing PMCA4b, PISP was unable to stimulate the PMCA-dependent ATPase activity. Our data suggest that PISP is a transiently interacting partner of the PMCA b-splice forms that may play a role in their sorting to or from the plasma membrane.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Goellner
authors.forename: Steven J
authors.initials: SJ
authors.lastname: DeMarco
authors.forename: Emanuel E
authors.initials: EE
authors.lastname: Strehler
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D027682:Cation Transport Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D004285:Dogs; D005091:Exons; D015723:Gene Library; D014644:Genetic Variation; D000077614:Golgi Matrix Proteins; D006801:Humans; D007438:Introns; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D053499:Plasma Membrane Calcium-Transporting ATPases; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D027682:Cation Transport Proteins; C434484:GOPC protein, human; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D053499:Plasma Membrane Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases