Growth hormone releasing hormone receptor.

Growth hormone releasing hormone receptor (GHRH-R) is a class II G protein-coupled receptor required for normal growth hormone (GH) synthesis and release from the pituitary, and for the normal growth and proliferation of somatotrophs within the pituitary. Mutations of this receptor in mouse and human are associated with GH deficiency, short stature, and pituitary hypoplasia. This signaling system plays important roles in growth and development, metabolism of muscle and fat, and, possibly, the aging process. Among topics touched on in this article are the receptor gene's organization and promoter regulation, receptor signaling pathways, and receptor domains involved in interaction with ligand. Also discussed are alternative mRNA splicing and proposed functions of these splice variants as dominant negative inhibitors of wild-type receptor and in tumor proliferation. Homology among GHRH-Rs from different species is shown and a map of receptor mutations reported to effect function is presented.