Plasma Membrane Ca2+-ATPase Isoforms 2b and 4b Interact Promiscuously and Selectively with Members of the Membrane-associated Guanylate Kinase Family of PDZ (PSD95/Dlg/ZO-1) Domain-containing Proteins

Abstract

Spatial and temporal regulation of intracellular Ca 2؉signaling depends on localized Ca 2؉ microdomains containing the requisite molecular components for Ca 2؉ influx, efflux, and signal transmission. Plasma membrane Ca 2؉ -ATPase (PMCA) isoforms of the "b" splice type contain predicted PDZ (PSD95/Dlg/ZO-1) interaction domains. The COOH-terminal tail of PMCA2b isolated the membrane-associated guanylate kinase (MAGUK) protein SAP97/hDlg as a binding partner in a yeast two-hybrid screen. The related MAGUKs SAP90/ PSD95, PSD93/chapsyn-110, SAP97, and SAP102 all bound to the COOH-terminal tail of PMCA4b, whereas only the first three bound to the tail of PMCA2b. Coimmunoprecipitations confirmed the interaction selectivity between PMCA4b and SAP102 as opposed to the promiscuity of PMCA2b and 4b in interacting with other SAPs. Confocal immunofluorescence microscopy revealed the exclusive presence and colocalization of PMCA4b and SAP97 in the basolateral membrane of polarized Madin-Darby canine kidney epithelial cells. In hippocampal neurons, PMCA2b was abundant throughout the somatodendritic compartment and often extended into the neck and head of individual spines where it colocalized with SAP90/PSD95. These data show that PMCA "b" splice forms interact promiscuously but also with specificity with different members of the PSD95 family of SAPs. PMCA-SAP interactions may play a role in the recruitment and maintenance of the PMCA at specific membrane domains involved in local Ca 2؉ regulation.Calcium ion (Ca 2ϩ ) homeostasis is crucial for cell function and survival (1). A finely controlled system of Ca 2ϩ transporters, channels, and Ca 2ϩ -binding proteins allows for transient increases in the intracellular free calcium concentration ([Ca 2ϩ ] i ), 1 while over the long term maintaining a low resting [Ca 2ϩ ] i (2). The exquisite specificity of Ca 2ϩ signaling mandates that both the entry and the removal of Ca 2ϩ are under precise temporal and spatial control (3, 4). Accordingly, the molecular machinery involved in local Ca 2ϩ signaling must be assembled, maintained, and regulated with the requisite spatial and temporal resolution. Mechanisms that increase local [Ca 2ϩ ] i have been studied extensively over the last few years; consequently, significant progress has been made in understanding the regulation and targeting of calcium channels (5). By contrast, much less is known about the spatial organization of Ca 2ϩ extrusion mechanisms, specifically that provided by plasma membrane Ca 2ϩ -ATPases (PMCAs). These primary ion pumps are essential for the long term maintenance of low intracellular Ca 2ϩ but more recently have also been implicated in dynamic events such as the regulation of Ca 2ϩ spikes and local Ca 2ϩ signaling (for review, see Refs. 6 -8). A multigene family of four non-allelic members encodes four conserved mammalian PMCA isoforms (designated PMCA1-4), with additional diversity generated by alternative mRNA splicing affecting the protein at two major locations (9). The four PMCA gene products do not ...

Histone deacetylase inhibitor- and PMA-induced upregulation of PMCA4b enhances Ca2+ clearance from MCF-7 breast cancer cells

“…On the other hand, PMCA4b binding to the α-1 syntrophin and nitric oxide synthase I can form a ternary complex, that modulates NO production and signaling in mouse heart tissue [68], in cerebellar granule cells [69,70] and in osteoclast differentiation [71]. Through the C-terminal tail, PMCA4b can bind to several PDZ proteins, such as SAP90/PSD95, SAP97, SAP102 [72], the Ania-3/Homer scaffold protein [73], that may arrange PMCA into specific membrane domains to regulate local Ca 2+ signaling. More recently, PMCA4 was shown to interact with STIM1 that influenced T-cell activation throught the activition of NFAT [74].…”

Formation of Complexes between Ca2+·Calmodulin and the Synapse-associated Protein SAP97 Requires the SH3 Domain-Guanylate Kinase Domain-connecting HOOK Region

“…DISCUSSION Understanding molecular mechanisms that govern complex macromolecular interactions is one of the major goals of structural biology. The interactions between the SAP97/hDlg multidomain protein, a member of the MAGUK protein family, and its putative binding partners have so far only been studied by qualitative or at best semi-quantitative cell biological methods using the yeast two-hybrid approach or co-immunoprecipitation techniques for detecting protein-protein association (21,42). Detailed studies of tertiary structures of MAGUKs have been confined to the C-terminal half of SAP90/PSD95 encompassing the SH3, HOOK, and GK domains (29,43), and our most recent work on human CASK has revealed distinctive structural features of the CASK GK binding module in comparison to enzymatically active guanylate kinase (19).…”

Ontogeny of plasma membrane Ca2+ ATPase isoforms in the neural retina of the postnatal rat

“…These include differences in kinetics, affinities for Ca 2ϩ and calmodulin, interactions with dics-large homology~PDZ! domaincontaining proteins, and susceptibility to modulation by second messengers~Caride et al, 2001;DeMarco & Strehler, 2001; reviewed in Guerini, 1998;Strehler & Zacharias, 2001!.…”