Accessory Proteins in the Biogenesis of G Protein-Coupled Receptors

The modification of GCPR ligand specificity by accessory proteins. Receptor activity–modifying proteins (RAMPs) are crucial not only to the delivery of calcitonin receptor–like receptor (CRLR), a seven-transmembrane GCPR, to the plasma membrane, but also determine the specificity of CRLR for ligand. Association of CRLR with RAMP1 results in a receptor for calcitonin gene–related peptide (CGRP), whereas association of CRLR with RAMP2 results in a receptor for adrenomedullin. [Image courtesy of Nature (www.nature.com). (See reference (25).]