cAMPPKAsignalvägen

cAMP signalvägen, also known as the cAMP-PKA pathway, is a fundamental cellular signaling mechanism involved in mediating responses to a wide variety of extracellular signals. This pathway is initiated when a signaling molecule, such as a hormone or neurotransmitter, binds to a specific G protein-coupled receptor (GPCR) on the cell surface. This binding event activates the associated G protein, which in turn activates adenylyl cyclase, an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) into cyclic adenosine monophosphate (cAMP). cAMP then acts as a second messenger within the cell.

The primary effector molecule of cAMP is protein kinase A (PKA), also known as cAMP-dependent protein kinase. cAMP binds to the regulatory subunits of PKA, causing a conformational change that releases the active catalytic subunits. These activated catalytic subunits can then phosphorylate a diverse range of target proteins, including enzymes, ion channels, transcription factors, and structural proteins. Phosphorylation by PKA can either activate or inhibit the function of these target proteins, thereby altering various cellular processes. These processes include, but are not limited to, metabolism, gene expression, muscle contraction, neuronal activity, and cell growth. The signaling cascade is typically terminated by phosphodiesterases, enzymes that hydrolyze cAMP into inactive adenosine monophosphate (AMP), thus allowing the cell to reset and respond to new signals. The cAMP-PKA pathway's ubiquity and versatility underscore its critical role in cellular communication and regulation.