Cyclic guanosine monophosphate-specific phosphodiesterase type 5 (PDE5)

Cyclic guanosine monophosphate-specific phosphodiesterase type 5 (PDE5) is an enzyme that catalyzes the hydrolysis of cGMP into inactive GMP. It plays a central role in regulating intracellular concentrations of cGMP—a key second messenger involved in mediating smooth muscle relaxation through nitric oxide signaling pathways. PDE5 is highly expressed in tissues such as the corpus cavernosum of the penis and clitoris, vascular smooth muscle cells throughout the body including those lining blood vessels in the lungs and heart, platelets, skeletal muscles, kidneys, bladder wall tissue as well as some regions within the brain.[1][4] Pharmacological inhibition of PDE5 increases local concentrations of cGMP leading to vasodilation—a mechanism exploited by drugs like sildenafil for treating erectile dysfunction and pulmonary arterial hypertension. The enzyme consists structurally of regulatory GAF domains that bind allosteric ligands like cGMP at its N-terminal region and a catalytic domain responsible for substrate hydrolysis at its C-terminal region.[3] Multiple isoforms exist due to alternative splicing but share similar functional properties. Selective inhibition has enabled significant therapeutic advances while minimizing side effects associated with non-selective phosphodiesterase inhibitors.[1]

Other names

Phosphodiesterase 5cGMP-specific phosphodiesterase type 5PDE5A (gene/protein isoform)Phosphodiesterase type 5

Drugs targeting this molecule act as competitive inhibitors at the catalytic site, preventing the breakdown of cGMP. This leads to increased intracellular cGMP levels, resulting in enhanced smooth muscle relaxation and vasodilation in target tissues such as the corpus cavernosum and pulmonary vasculature.[1][3][4]