The Prokineticins (PK1 and PK2) are a pair of cysteine-rich secreted peptides with broad physiological functions including gastrointestinal motility, angiogenesis, hematopoiesis and circadian rhythms regulation.nThe biological effects of the PK1 and PK2 are mediated by two highly homologous receptors termed Prokineticin Receptor 1 (PKR1) and Prokineticin Receptor 2 (PKR2) that belong to the 7-transmembrane domain, G protein-coupled receptor (GPCR) superfamily. Both PK ligands activate the two PK receptors with similar potency.nPKR1 receptors couple to Gq/G11 proteins leading to phospholipase C activation, inositol phosphate production and calcium mobilization. In addition, activation of the mitogen-activated protein kinase (MAPK) pathways has also been described.
