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Protein protein interaction motifs in G-protein coupled receptors 

Interactions in GPCR:

G-protein, kinase, arrestin, scaffolding

Proteomic approaches have identified additional structural/scaffolding proteins: see reference Becamel et al. (2002), review: Kreienkamp (2002)

I. PDZ domain interaction motifs in GPCR

- general information on PDZ domains in membrane proteins

- motif for type 1 PDZ domain binding has been found in all 5 subtypes of somatostatin receptor and for type 2 PDZ in mGluR7a, PrRP, k-opioid

- experimental demonstration of association of PDZ (type 1 or 2) domains with GPCR in several systems (references 10-21 and Table 1 in Kreienkamp (2002))

        - Receptor:                                                                                - Sequence                - PDZ domain protein

        - rat somatostatin receptor subtype 2                                        NGDLQTSIstop        - shank/ProSAP/SSTRIP

        - beta 1-adrenergic receptor                                                     GFASESKVstop        - PDS-95, PDZ3

        - beta 2-adrenergic receptor                                                     CSTNDSLLstop        - NHE-RF

        - serotonin 2B receptor                                                                                               - 

        - serotonin 5-hydroxytryptamine type 2C (5-HT_2C) receptor   VSERISSVstop          - MUPP

        - calcium-independent alpha-latrotoxin receptor (CIRL)         MQLVTSLstop          -  shank/ProSAP/SSTRIP

        - CL1                                                                                                                           - 

        - Group 1 metabotropic glutamate receptors                            YKQSSSTLstop        -  shank/ProSAP/SSTRIP/tamalin/GRASP                 

        - Group 7a metabotropic glutamate receptor                           VSYNNLVIsto          -   PICK      

        - BAI1                                                                                      IIDLQTEVstop         -  PSD-95                 

        - prolactin releasing peptide (PrRP)                                        NMTVSVVIstop        - GRIP, PICK            

        - k opioid                                                                                 IDMGNKPVstop       - NHE-RF                       

  - regulation via phosphorylation at S or T in X-[ST]-X-F-stop, shown in beta1-AR (ref. 14 in Kreienkamp (2002))

- most PDZ domain proteins are part of multidomain proteins and function in GPCR via the other domains, example PSD-95 (= synapse-associated protein SAP-90) has 3xPDZ, one src homology (SH3) domain and one guanylate kinase domain (ref Kreienkamp (2002))

- 50 intracellular and membrane proteins have high affinity for the PDZ domains of PSD-95, several in G-protein mediated signaling (get ref. Lim, Hall and Hell, 2002)

- experimental identification of PDZ interaction: 

        1. yeast-2-hybrid

        2. affinity chromatography plus mass spec (MALDI or ESI plus TOF) [PDZ domain very stable, can do experiment under harsh conditions, e.g. 2% SDS, or pH9             Na-desoxycholate cell extract, run over immobilized C-terminal peptides]

- unusual PDZ binding motif: get ref. Li, Ehn, Liu-Chen (2002) EBP50/NHERF blocks U50,488H induced down-rgulation of the human kappap opioid receptor by enhancing its recylcing rate. JBC

Motifs in GPCR:

PDZ domain-binding motifs in GPCR:

D/E R Y sequence in GPCR: