Which second messenger plays a critical role in the activation of protein kinase A?

Which second messenger plays a critical role in the activation of protein kinase A?

• A. cGMP
• B. IP3
• C. cAMP
• D. Calcium ions

Answer: (C)

The second messenger that plays a critical role in the activation of protein kinase A (PKA) is cyclic adenosine monophosphate (cAMP). PKA is an important enzyme that is involved in the phosphorylation of various target proteins, leading to changes in their activity, localization, or interactions with other proteins within the cell. When a signaling molecule, such as a hormone, binds to a G protein-coupled receptor on the cell surface, it activates an associated G protein, which in turn activates adenylate cyclase. This enzyme catalyzes the conversion of ATP to cAMP. The increase in intracellular levels of cAMP then binds to the regulatory subunits of PKA, causing a conformational change that releases the catalytic subunits of the enzyme. Once released, these catalytic subunits are active and can phosphorylate target proteins on serine and threonine residues, triggering various cellular responses. The other options, while also involved in cell signaling processes, do not specifically activate PKA. cGMP, for instance, is primarily associated with the activation of protein kinase G (PKG) and has different target proteins than those modulated by PKA. IP3 is a second messenger that primarily functions to increase calcium levels within

The second messenger that plays a critical role in the activation of protein kinase A (PKA) is cyclic adenosine monophosphate (cAMP). PKA is an important enzyme that is involved in the phosphorylation of various target proteins, leading to changes in their activity, localization, or interactions with other proteins within the cell.

When a signaling molecule, such as a hormone, binds to a G protein-coupled receptor on the cell surface, it activates an associated G protein, which in turn activates adenylate cyclase. This enzyme catalyzes the conversion of ATP to cAMP. The increase in intracellular levels of cAMP then binds to the regulatory subunits of PKA, causing a conformational change that releases the catalytic subunits of the enzyme. Once released, these catalytic subunits are active and can phosphorylate target proteins on serine and threonine residues, triggering various cellular responses.

The other options, while also involved in cell signaling processes, do not specifically activate PKA. cGMP, for instance, is primarily associated with the activation of protein kinase G (PKG) and has different target proteins than those modulated by PKA. IP3 is a second messenger that primarily functions to increase calcium levels within