Prokineticin Receptor 1 (PKR1), also called ZAQ or GPR73a (G-protein coupled receptor 73a), is a 7-transmembrane glycoprotein of the GPCR family. The extracellular portions of human PKR1 share 81% and 78% aa identity with corresponding portions of mouse PKR1 and human PKR2, with non-identity mainly in the N-terminal sequences. Both PKR1 and PKR2 mediate the effects of prokineticins 1 and 2. This includes mitogenic regulation of angiogenesis in endocrine glands and stimulation of contraction in gastrointestinal smooth muscle.