Isolation and characterization of a dimeric cAMP-dependent protein kinase from the fungus Saccobolus platensis.
A cAMP-dependent protein kinase from mycelia of Saccobolus platensis was characterized. The holoenzyme seems to be a dimer (i.e., regulatory subunit--catalytic subunit) of 78,000 Da, slightly activated by cAMP but susceptible to dissociation into its subunits by cAMP, or by kemptide and protamine, the best substrates for Saccobolus protein kinase. The regulatory subunit was purified to homogeneity by affinity chromatography. It is highly specific for cAMP and has two types of binding sites but failed to inhibit the phosphotransferase activity of the homologous or the heterologous (bovine heart) catalytic components. The activity of the catalytic subunit was completely abolished by the regulatory component of the bovine heart protein kinase as well as by a synthetic peptide corresponding to the active site of the mammalian protein kinase inhibitor. The data suggest that interaction between the subunits of the S. platensis protein kinase is different than that found in cAMP-dependent protein kinases from other sources. Similarities and differences between the Saccobolus protein kinase and enzymes from low eucaryotes and mammalian tissues are discussed.
Silberstein
S
S
Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Ciudad Universitaria, Argentina.
Cantore
M L
ML
Galvagno
M A
MA
Passeron
S
S
D001203:Ascomycota / Q000201:enzymology*; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D011487:Protein Conformation; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity
D046911:Macromolecular Substances; D000242:Cyclic AMP; D011494:Protein Kinases