guanililciclasa

Guanililciclasa, more commonly known as guanylyl cyclase or guanylate cyclase, is an enzyme that catalyzes the conversion of guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP), a key second messenger in many signaling pathways. The reaction also yields pyrophosphate as a byproduct and helps regulate the intracellular levels of cGMP, which in turn modulates a variety of cellular responses.

There are two major classes of guanylyl cyclases: soluble guanylyl cyclase (sGC) and membrane-bound, or particulate, guanylyl cyclase (pGC). sGC is a cytosolic, heme-containing enzyme typically activated by nitric oxide (NO). When NO binds to the heme group of sGC, its catalytic activity increases, leading to elevated cGMP levels and downstream effects such as smooth muscle relaxation, neurotransmission, and inhibition of platelet aggregation. pGCs are single-pass transmembrane receptors that function as extracellular ligand-binding proteins linked to intracellular catalytic domains. They are commonly activated by peptide hormones such as natriuretic peptides (for example, ANP and BNP) and thereby raise intracellular cGMP to regulate cardiovascular and renal physiology.

In the retina, specialized guanylyl cyclases participate in phototransduction, helping restore photoreceptor sensitivity after exposure to light. Regulation of guanylyl cyclases involves calcium-binding proteins and other modulators to finely tune cGMP signaling.

Guanylyl cyclases play essential roles in cardiovascular function, sensory perception, and neural signaling. Dysregulation can contribute to disease, making these enzymes important targets for therapeutic strategies aimed at blood pressure control, heart failure, and related conditions.