Adenosine Cyclic Monophosphate Dependent Protein Kinases, also known as cyclic AMP-dependent protein kinases or protein kinase A (PKA), are a group of enzymes that play a crucial role in intracellular signaling pathways. They are typically found in eukaryotic cells and are involved in the regulation of various cellular processes.
The name "adenosine cyclic monophosphate dependent" refers to the fact that these protein kinases require the presence of cyclic adenosine monophosphate (cAMP) in order to carry out their functions. Cyclic AMP is a second messenger molecule that acts as a signaling molecule within cells. When a particular extracellular signal activates a G protein-coupled receptor, it triggers the production of cAMP, which then activates PKA.
Once activated, PKA phosphorylates target proteins by transferring a phosphate group from adenosine triphosphate (ATP) to specific residues on these proteins. This process is called phosphorylation and can induce conformational changes in the target proteins, thereby altering their activity or function. By phosphorylating target proteins, PKA plays a vital role in the regulation of cellular processes such as metabolism, gene expression, cell growth, and cell division.
PKA is composed of two regulatory subunits and two catalytic subunits. In the absence of cAMP, the regulatory subunits inhibit the catalytic subunits, preventing them from phosphorylating target proteins. However, when cAMP binds to the regulatory subunits, they dissociate from the catalytic subunits, allowing the catalytic subunits to become active and initiate phosphorylation.
Overall, adenosine cyclic monophosphate dependent protein kinases are critical components of cellular signaling pathways, serving as key regulators of numerous cellular processes by phosphorylating
