The prokineticin receptors, PKR1 (GPR73a) and PKR2 (GPR73b), are G protein-coupled receptors responsible for mediating the signal transduction of both EG-VEGF and Prokineticin-2. PKR1 and PKR2 share 87% sequence identity. PKR1 is predominantly expressed in the peripheral tissues and PKR2 is typically expressed in the CNS. Both receptors are found in the testis. Upon ligand binding, PKR1 and PKR2 associate with G protein and can promote intracellular calcium mobilization, stimulate phosphoinositide turnover and activate the MAPK pathway. These receptors play a role in a variety of physiological events such as intestinal contraction, ingestive behavior, spermatogenesis, angiogenesis, circadian rhythm, neuronal survival and hyperalgesia. PKR1 may promote cardiomyocyte survival. PKR2 is essential for the normal development of the olfactory bulb. Mutations in the gene encoding PKR2 may result in Kallmann syndrome type 3.