Molecular Cloning and Characterization of the Porcine Calcitonin Gene-Related Peptide Receptor

Calcitonin gene-related peptide (CGRP) receptors (CGRP-Rs) are widely distributed throughout the central and peripheral nervous systems. A novel CGRP-R was identified from a porcine lung complementary DNA library. Sequence analysis indicated that the CGRP-R is 462 amino acids in length and shares 93% sequence identity with the human CGRP-R. Northern blot analysis indicated a messenger RNA species of 5.4 kilobases, which is abundantly expressed in the lung. Ligand binding studies of the cloned CGRP-R expressed in human embryonic kidney (HEK-293) cells showed the presence of high affinity receptor for CGRP with a Kd of 38.5 pm. The pharmacological profiles of various ligands competing for [125I]CGRP binding to the expressed receptor were in accordance with those for the natural receptor. Binding of [125I]CGRP to the expressed receptor was decreased in the presence of a nonhydrolyzable analog of GTP, guanosine 5′ (γ-thio)-triphosphate. In functional studies, CGRP stimulated the activation of adenylyl cyclase...