Cloning, characterization, and expression of a calcitonin receptor from guinea pig brain.

A calcitonin receptor was cloned from guinea pig brain by using a degenerate reverse transcription-polymerase chain reaction (RT-PCR) strategy. When the cloned guinea pig calcitonin receptor was transfected into COS 1 cells, salmon calcitonin stimulated intracellular cyclic AMP accumulation with an EC50 of 0.1 nM, whereas human calcitonin was >250-fold less potent (EC50 27.6 nM). Related neuropeptides rat alphaCGRP and rat amylin did not activate the guinea pig calcitonin receptor at physiologic concentrations. Stimulation of the transfected guinea pig calcitonin receptor by salmon calcitonin also resulted in phosphatidylinositol hydrolysis with an EC50 of 2.5 nM. Expression of the calcitonin receptor was mapped by a combination of RT-PCR, northern analysis, and expression in Xenopus oocytes. The guinea pig calcitonin receptor was most highly expressed in diencephalon and a single subtype was detected.