title: Regulation of cyclic AMP phosphodiesterase from Mucor rouxii by phosphorylation and proteolysis. Interrelationship of the activatable and insensitive forms of the enzyme.
abstract: DEAE-cellulose chromatography of mycelial extracts of Mucor rouxii grown to mid-exponential phase resolves two types of low-Km cyclic AMP phosphodiesterase (EC 3.1.4.17; PDE): PDE I, highly activatable (4-6-fold) by phosphorylation or proteolysis, and PDE II, unresponsive to activation. The enzymic profile of PDE activity obtained from germlings shows only PDE I activity, whereas PDE activity from mycelia grown to stationary phase is eluted from the DEAE-cellulose column at the position of PDE II, and like PDE II is unresponsive to activation. Endogenous proteolysis or controlled trypsin treatment transforms PDE I into PDE II. The insensitive forms of PDE exhibit a slightly smaller sedimentation coefficient than the activatable forms, as judged by sucrose-gradient centrifugation. The basal activity of the highly activatable form of PDE is elevated almost to the value in the presence of trypsin on storage at 4 degrees C in the absence of proteinase inhibitors. Benzamidine, leupeptin, antipain or EGTA prevents the activation produced by storage. PDE I remains strongly activatable by phosphorylation and proteolysis after resolution by polyacrylamide-gel electrophoresis.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D002848:Chromatography, DEAE-Cellulose; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism; D009089:Mucor / Q000201:enzymology* / Q000254:growth & development; D010766:Phosphorylation; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D007527:Isoenzymes; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D014357:Trypsin