title: PSD-95 mediates membrane clustering of the human plasma membrane Ca2+ pump isoform 4b.
abstract: Besides the control of global calcium changes, specific plasma membrane calcium ATPase (PMCA) isoforms are involved in the regulation of local calcium signals. Although local calcium signaling requires the confinement of signaling molecules into microdomains, little is known about the specific organization of PMCA molecules within the plasma membrane. Here we show that co-expression with the postsynaptic density-95 (PSD-95) scaffolding protein increased the plasma membrane expression of PMCA4b and redistributed the pump into clusters. The clustering of PMCA4b was fully dependent on the presence of its PDZ-binding sequence. Using the fluorescence recovery after photobleaching (FRAP) technique, we show that the lateral membrane mobility of the clustered PMCA4b is significantly lower than that of the non-clustered molecules. Disruption of the actin-based cytoskeleton by cytochalasin D resulted in increased cluster size. Our results suggest that PSD-95 promotes the formation of high-density PMCA4b microdomains in the plasma membrane and that the membrane cytoskeleton plays an important role in the regulation of this process.
authors.affiliation: National Blood Center, Department of Molecular Cell Biology, Diószegi u. 64, H-1113 Budapest, Hungary.
authors.forename: Rita
authors.initials: R
authors.lastname: Padányi
authors.forename: Katalin
authors.initials: K
authors.lastname: Pászty
authors.forename: Emanuel E
authors.initials: EE
authors.lastname: Strehler
authors.forename: Agnes
authors.initials: A
authors.lastname: Enyedi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D051528:Guanylate Kinases; C507517:ATP2B4 protein, human; D053499:Plasma Membrane Calcium-Transporting ATPases; D002118:Calcium