CRF1 and CRF2 receptors are both members of the Class B/secretin family of heptahelical receptors, and are encoded by Crhr1 and Crhr2 genes, respectively. The Crhr2 gene gives rise to at least two alternatively spliced isoforms: CRF2(a), expressed in neurons, and CRF2(b), expressed in peripheral tissues and non-neuronal brain structures (Bale and Vale, 2004). CRF2(a) and CRF1 receptors share about 70% amino acid homology, with a particularly high degree of conservation in regions thought to be the primary site of G-protein coupling and signal transduction. Functional specificity of the CRF receptors appears to arise from their distinct cellular expression patterns, anatomical distributions, or both.
