Characterization, tissue distribution and biological activity of the novel neuropeptide secretoneurin

Abstract

other. Each group shows marked sequence similarities in their putative transmembrane spanning regions, whereas the two groups are structurally different from each other. Operational information suggests a similar subdivision, since the pharmacological profiles of SSTRliSSTR4 receptors (virtually no affinity for octreotide, seglitide, RC 160) are markedly different from the profiles of SSTR2/SSTR-3/SSTR-5 receptors (intermediate to very high affinity for these compounds). The previously termed SS1 or SRIF-1 receptors correspond to the SSTR-2 receptors, whereas the SSTR-1 receptor is equivalent to SS-2 and presumably to SRIF-2 receptors (both initially defined by their lack of afIinity for octreotide and seglitide). Transductional information shows that all 5 cloned receptors couple negatively to adenylyl cyclase activity. Since all cloned receptors have similarly high affinity for SRIF14 and -28, the following nomenclature can be proposed: 3 subtypes of SRIF-1 (lA, lB, 1C) receptors (SSTR-2, -5 and -3) and 2 subtypes of SRIF-2 (2A, 2B) receptors (SSTR-1 and -4). Operational, structural and transductional data in support of the present proposal, as well as brain distribution of the different receptors wilI be presented.