Agonist-dependent interaction of the rat somatostatin receptor subtype 2 with cortactin-binding protein 1

We report here an interaction between the C terminus of the rat somatostati n receptor subtype 2 (SSTR2) and a protein that has recently been identifie d as contactin-binding protein 1 (CortBP1). Interaction is mediated by the PDZ (PSD-95/discs large/ZO-1) domain of CortBP1. As shown by in situ hybrid ization, SSTR2 and cortactin-binding protein are coexpressed in the rat bra in. The association between SSTR2 and the PDZ-domain of CortBP1 was verifie d by overlay assays and by coprecipitation after transfection in human embr yonic kidney (HEK) cells. Analysis by confocal microscopy indicates that Co rtBP1 is distributed diffusely throughout the cytosol in transfected cells and that it becomes concentrated at the plasma membrane when SSTR2 is prese nt. This process is largely increased when the receptor is stimulated by so matostatin; as CortBP1 interacts with the C terminus of SSTR2, our data sug gest that the binding of agonist to the receptor increase the accessibility of the receptor C terminus to the PDZ domain of CortBP1. Our data for the first time establish a link between a G-protein coupled receptor and consti tuents of the cytoskeleton.