The G Protein-coupled Receptor CL1 Interacts Directly with Proteins of the Shank Family

Abstract

PDZ domains play a pivotal role in the synaptic localization of ion channels, receptors, signaling enzymes, and cell adhesion molecules. These domains mediate protein-protein interactions via the recognition of a conserved sequence motif at the extreme C terminus of their target proteins. By means of a yeast two-hybrid screen using the C terminus of the G protein-coupled ␣-latrotoxin receptor CL1 as bait, three PDZ domain proteins of the Shank family were identified. These proteins belong to a single protein family characterized by a common domain organization. The PDZ domain is highly conserved among the family members, significantly different from other known PDZ domains, and specifically binds to the C terminus of CL1. Shank1 and CL1 are expressed primarily in brain, and both proteins co-enrich in the postsynaptic density. Furthermore, Shank1 induces a clustering of CL1 in transfected cells, strongly supporting an interaction of both proteins in vivo.A large class of proteins containing PDZ domains play a general role in the localization of ion channels, signaling molecules, and adhesion molecules to synapses (1-4). These functions are exemplified by the defining family of PDZ domain proteins (PSD-95, Dlg, and ZO-1), known as membrane-associated guanylate kinases (MAGUKs).1 MAGUK proteins include PSD-95/SAP-90 and the closely related PSD-93/chapsyn-110, SAP-97/hdlg, and SAP-102, all of which are found at synapses in brain; the Drosophila PSD-95/SAP-90 homolog, DLG A, which localizes to septate junctions and larval neuromuscular junctions; and ZO-1 and ZO-2, both of which associate with tight junctions between epithelial cells. MAGUKs share a common domain organization, with one or three N-terminal PDZ domains, an SH3 domain, and a C-terminal region homologous to guanylate kinases. PDZ domains mediate protein-protein interactions and typically bind to short amino acid motifs at the

PDZ Protein Regulation of G Protein–Coupled Receptor Trafficking and Signaling Pathways

“…Similarly, Shank1/3 modulates muscarinic acetylcholine receptor 1-and D 2 R-mediated inhibition of L-type Ca 21 channels via Homer proteins (Olson et al, 2005). With regards to GPCR trafficking, Shank influences the clustering and subcellular localization of mGluR5 and calcium-independent a-latrotoxin receptor CIRL/latrophilin 1 (Tu et al, 1999;Tobaben et al, 2000). Interestingly, a Shank/Homer1A complex can suppress NMDAR and AMPAR clustering and surface expression (Sala et al, 2003).…”

Cortactin: coupling membrane dynamics to cortical actin assembly

“…Shank proteins serve as molecular sca olds at postsynaptic sites (PSD) of excitatory synapses, and are characterized by the presence of an amino-terminal PSD95/dlg/ZO-1 (PDZ) domain. The CortBP1 PDZ domain directly binds to the carboxyl terminus of the transmembrane type 2 somatostatin receptor (Zitzer et al, 1999) and the a-latrotoxin receptor CL1 (Kreienkamp et al, 2000;Tobaben et al, 2000). In addition, Shank1 and Shank3 contain a set of seven ankyrin repeats and an SH3 domain proximal to the PDZ domain (Sheng and Kim, 2000).…”

Linkage of the Actin Cytoskeleton to the Postsynaptic Density via Direct Interactions of Abp1 with the ProSAP/Shank Family

“…ProSAP/Shank proteins represent a protein family currently comprising three isoforms encoded by different genes and multiple splice variants of these isoforms (for review, see Boeckers et al, 2002). ProSAP1 (Boeckers et al, 1999a) corresponds to CortBP1 (cortactin-binding protein 1) (Du et al, 1998), Shank2 Tu et al, 1999), and Spank3 (Tobaben et al, 2000). The ProSAP2 isoform (Boeckers et al, 1999b) corresponds to Shank3 Tu et al, 1999) and Spank1 (Tobaben et al, 2000).…”

“…ProSAP1 (Boeckers et al, 1999a) corresponds to CortBP1 (cortactin-binding protein 1) (Du et al, 1998), Shank2 Tu et al, 1999), and Spank3 (Tobaben et al, 2000). The ProSAP2 isoform (Boeckers et al, 1999b) corresponds to Shank3 Tu et al, 1999) and Spank1 (Tobaben et al, 2000). The third isoform is referred to as Shank1 , Synamon , SSTRIP (somatostatin receptor interactive protein) (Zitzer et al, 1999), and Spank2 (Tobaben et al, 2000).…”

“…The ProSAP2 isoform (Boeckers et al, 1999b) corresponds to Shank3 Tu et al, 1999) and Spank1 (Tobaben et al, 2000). The third isoform is referred to as Shank1 , Synamon , SSTRIP (somatostatin receptor interactive protein) (Zitzer et al, 1999), and Spank2 (Tobaben et al, 2000). We tested Abp1 binding with both antiProSAP1 (Fig.…”