PKG

PKG is a cyclic guanosine monophosphate (cGMP) -dependent serine/threonine kinase, which is activated by cGMP, phosphorylates the substrates, and regulates intracellular signal transduction. PKG inhibits β-catenin and cyclin D1 and regulates cell growth and apoptosis. PKG phosphorylates myosin light chains in smooth muscle cells, causing smooth muscle relaxation, thereby regulating vasodilation and blood pressure. PKG phosphorylates calcium channels for calcium homeostasis regulation. PKG regulates gene expression by phosphorylating transcription factors, thereby affecting cell differentiation and proliferation. PKG also regulates circadian rhythm, anxiety and fear memory. PKG has 2 subtypes, PKG I and PKG II. PKG I is mainly expressed in smooth muscle, platelets and specific neuronal areas, participates in vascular smooth muscle relaxation and cardiac function regulation. PKG II is mainly expressed in intestinal secretory epithelial cells, juxtaglomerular cells, adrenal cortex, chondrocytes and suprachiasmatic nucleus, which is mainly involved in the regulation of kidney and adrenal function, as well as bone growth and development. PKG dysfunction could lead to cancer, neurological or cardiovascular diseases^[1][2][3].