Adenylátcykláza

Adenylátcykláza, often abbreviated as AC, is a crucial enzyme found in many cell types. Its primary function is to catalyze the synthesis of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). This reaction is a key step in cellular signal transduction pathways, allowing cells to respond to a wide range of external stimuli.

The activity of adenylátcykláza is tightly regulated. It can be activated or inhibited by various signaling molecules, including hormones and neurotransmitters, which bind to specific receptors on the cell surface. These receptors are often coupled to G proteins, which in turn modulate the enzyme's activity. For instance, binding of a hormone like adrenaline to its receptor can lead to the activation of adenylátcykláza, increasing intracellular cAMP levels. Conversely, other signals can inhibit the enzyme, reducing cAMP production.

Cyclic AMP acts as a second messenger, relaying signals from the cell surface to intracellular targets. One of its most important roles is to activate protein kinase A (PKA), a serine/threonine kinase that phosphorylates numerous proteins, thereby altering their activity. This cascade of events influences a vast array of cellular processes, including metabolism, gene expression, muscle contraction, and neuronal activity. The precise effects of cAMP depend on the specific cell type and the proteins it ultimately influences.