title: SH3 ligands in the dopamine D3 receptor.
abstract: It has recently been observed that G protein-coupled receptors (GPCRs) can interact with SH3 domains through polyproline motifs. These interactions appear to be involved in receptor internalization and MAPK signalling. Here we report that the third cytoplasmic loop of the dopamine D3 receptor can interact in vitro with the adaptor protein Grb2. While the amino- and carboxy-terminal SH3 domains of Grb2 separately did not interact with the D3 receptor loop, the interaction is at least partially maintained with a Grb2 mutant for the amino-terminal SH3 domain, but disrupted for a Grb2 mutant with a nonfunctional carboxy-terminal SH3 domain. The data indicate the need of structural integrity of the entire Grb2 protein for the interaction and dominant role of the carboxy-terminal SH3 domain in the interaction. Disruption of the PXXP motifs in the D3 receptor did not affect the interaction with Grb2. These results indicate that GPCRs may contain SH3 ligands that do not contain the postulated minimal consensus sequence PXXP.
authors.affiliation: Laboratory of Molecular Neurobiology, Centre for Addiction and Mental Health, M5T 1R8, Toronto, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Oldenhof
authors.forename: A
authors.initials: A
authors.lastname: Ray
authors.forename: R
authors.initials: R
authors.lastname: Vickery
authors.forename: H H
authors.initials: HH
authors.lastname: Van Tol
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D006224:Cricetinae; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D051380:GRB2 Adaptor Protein; D005982:Glutathione Transferase / Q000378:metabolism; D008024:Ligands; D020935:MAP Kinase Signaling System; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000737:chemistry*; D050637:Receptors, Dopamine D3; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; D008024:Ligands; D011506:Proteins; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase