cGMP-dependent protein kinase type I alpha (PKG1α)

cGMP-dependent protein kinase type I alpha (PKG1α) is a serine/threonine-specific protein kinase that serves as a key mediator of cGMP signaling in mammalian cells. It is one of two primary PKG1 isoforms, resulting from alternative splicing, and is more sensitive to cGMP than the β isoform. PKG1α is predominantly found in the cytoplasm of cells such as vascular and visceral smooth muscle, lung, heart, nervous tissue, and is involved in the regulation of smooth muscle tone, vascular relaxation, blood pressure, platelet function, and metabolic processes. The kinase is activated via cGMP-induced conformational changes, but can also be regulated allosterically by small molecules or through redox modifications. PKG1α is a target of therapeutic interest in diseases such as pulmonary arterial hypertension, cardiovascular disorders, and sensorineural hearing loss. Its activity is often modulated by drugs affecting cGMP levels such as PDE5 inhibitors (e.g., sildenafil and vardenafil), which indirectly activate PKG1α by increasing cGMP. The enzyme's activation and downstream phosphorylation events regulate multiple cellular processes critical to vascular tone, cell proliferation, and gene expression. Safety concerns of targeting this kinase include hypotension and effects on non-target smooth muscle and sensory systems.

Other names

cGMP-dependent protein kinase I-αPKG IαProtein kinase G type I alphaPRKG1 (gene-level for type I family)

Activation by cGMP binding (causing conformational change, relieving autoinhibition, leading to phosphorylation of substrate proteins); Allosteric activation by small molecules (targeting allosteric sites, causing kinase activation independently of cGMP); Redox regulation via interprotein disulfide formation affecting kinase activity