Phosphodiesterase 4D isoform 5 (Ser54Asp mutant) (PDE4D5-S54D)

Phosphodiesterase 4D isoform 5 (PDE4D5) is a specific splice variant of the PDE4D gene, which encodes an enzyme responsible for the hydrolysis of the second messenger cyclic adenosine monophosphate (cAMP) (UniProt Q08499). The S54D designation refers to a phosphomimetic mutation at Serine 54, a residue located within the Upstream Conserved Region 1 (UCR1) that is a primary target for phosphorylation by Protein Kinase A (PKA) (Hoffmann et al., 1998, EMBO J). This mutation mimics the PKA-phosphorylated, activated state of the enzyme, serving as a critical negative feedback mechanism to terminate cAMP signaling (Sette and Conti, 1996, J. Biol. Chem.). PDE4D5 is uniquely characterized by its N-terminal domain, which facilitates interactions with signaling scaffold proteins such as RACK1 and beta-arrestin, thereby directing the enzyme to specific subcellular compartments like the plasma membrane (Bolger et al., 2003, Biochem. J.). In therapeutic contexts, PDE4D is a major target for anti-inflammatory drugs used in respiratory diseases like asthma and COPD, where it modulates the activity of immune and smooth muscle cells (Giembycz, 2008, Biochem. Pharmacol.). The enzyme is also a focus of research in neurobiology, particularly regarding cognitive enhancement and stroke recovery (Houslay et al., 2005, Drug Discov. Today). Pharmacological targeting involves small molecule inhibitors like roflumilast, which competitively bind the catalytic site; however, clinical use is often limited by side effects such as emesis, likely mediated by PDE4D inhibition in the central nervous system (Robichaud et al., 2002, J. Clin. Invest.).

Other names

cAMP-specific 3',5'-cyclic phosphodiesterase 4D isoform 5 S54DPDE4D5 phosphomimeticSer54Asp PDE4D5 mutantPDE4D5 S54D

Inhibition of cAMP-specific phosphodiesterase activity, leading to increased intracellular cAMP levels and subsequent activation of protein kinase A (PKA) and other downstream effectors.