Identification of proteins interacting with the rat somatostatin receptor subtype 2

Using the yeast two hybrid system we have identified a novel protein termed somatostatin receptor interacting protein (SSTRIP) from human brain which interacts with the rat somatostatin receptor subtype 2. Interaction with the receptor C-terminus is mediated by a PSD-95/discs large/ZO-1 (PDZ) domain which exhibits high similarity to the PDZ domain of cortactin binding protein 1 (CortBP1). SSTRIP and CortBP1 define a novel family of multidomain proteins containing ankyrin repeats, SH3- and SH3 binding regions and a sterile alpha motif (SAM domain) in addition to the PDZ domain. Both SSTRIP and CortBP1 can be co-immunoprecipitated with the somatostatin receptor when co-expressed in HEK cells. Interestingly, co-localization of SSTR2 and CortBP1 at the plasma membrane is increased when SSTR2 is stimulated by agonists.