Functional Structure of the Secretin Receptor

Secretin is a 27 amino acid peptide secreted by specialised endocrine cells of the gut that regulates the pancreatic exocrine - and the liver bile secretions. Its role as a neuropeptide is likely but not yet proven. Secretin acts through interaction with a membrane receptor coupled to the Gαsprotein and thus stimulates cyclic AMP production. It belongs to a new subgroup of receptors named the GPCRB that includes - among others - the VIP, the PACAP, the Glucagon, the Glucagon like peptide 1, the Calcitonin and the Parathormone receptors. The expression in CHO cells of the wild type and of mutated receptors permits the identification of domains involved in ligand recognition, in signal transduction, in desensitisation and in receptor intemalisation.