title: Phosphorylation of phosphodiesterase-5 is promoted by a conformational change induced by sildenafil, vardenafil, or tadalafil.
abstract: Phosphodiesterase-5 (PDE5) inhibitors (sildenafil, vardenafil, or tadalafil) or phosphorylation by cyclic nucleotide-dependent protein kinase causes an apparent conformational change in PDE5, as indicated by a shift in migration on non-denaturing PAGE gels and an altered pattern of tryptic digestion. Combination of cGMP and a PDE5 inhibitor or phosphorylation does not cause a further gel shift or change in tryptic digest. Phosphorylation of PDE5 is stimulated by inhibitors, and combination of cGMP and inhibitor does not cause further phosphorylation. Dephosphorylation of PDE5 by either purified phosphoprotein phosphatase-1 or -2A catalytic subunit or by a crude phosphatase mixture is not affected by cGMP or inhibitors, suggesting that phosphorylation itself maintains conformational exposure of the phosphorylation site. The combined results imply that cGMP binding to the catalytic site initiates negative feedback control of many cellular cGMP signaling pathways by directly stimulating phosphorylation and activation of PDE5; by exploiting this molecular mechanism, PDE5 inhibitors stimulate their own potencies.
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.
authors.forename: Emmanuel P
authors.initials: EP
authors.lastname: Bessay
authors.forename: Roya
authors.initials: R
authors.lastname: Zoraghi
authors.forename: Mitsi A
authors.initials: MA
authors.lastname: Blount
authors.forename: Kennard A
authors.initials: KA
authors.lastname: Grimes
authors.forename: Alfreda
authors.initials: A
authors.lastname: Beasley
authors.forename: Sharron H
authors.initials: SH
authors.lastname: Francis
authors.forename: Jackie D
authors.initials: JD
authors.lastname: Corbin
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002243:Carbolines / Q000494:pharmacology; D020134:Catalytic Domain; D006152:Cyclic GMP / Q000378:metabolism; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008024:Ligands; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D054645:Protein Phosphatase 1; D011687:Purines / Q000494:pharmacology; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology; D000068581:Tadalafil; D014227:Triazines / Q000494:pharmacology; D014357:Trypsin; D000069058:Vardenafil Dihydrochloride
chemical_list: D002243:Carbolines; D007093:Imidazoles; D008024:Ligands; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human; D014357:Trypsin; D006152:Cyclic GMP