title: Phosphorylation of protein B-50 (GAP-43) from adult rat brain cortex by casein kinase II.
abstract: The phosphoprotein B-50 (GAP-43) was purified from adult rat brain cortex and phosphorylated by casein kinase II. Phosphorylation of B-50 by casein kinase II approached 1.2 mol phosphate/mol B-50. The apparent Km of casein kinase II for B-50 was 4 microM with an apparent Vmax of 13 nmol.min-1.mg-1. A tryptic phosphopeptide map on reversed phase HPLC and phosphoamino acid analysis of [32P]B-50 showed that casein kinase II phosphorylated in serine residue(s) which were located in a single tryptic peptide. Phosphorylation of B-50 by casein kinase II was inhibited more than 90% by 5 micrograms heparin/ml or 2.4 mM peptide substrate specific for casein kinase II (RRREEETEEE). The initial phosphorylation rate was increased about 2-fold by 1 mM spermine.
authors.affiliation: Department of Biochemistry, Medical College of Ohio, Toledo 43699.
authors.forename: M R
authors.initials: MR
authors.lastname: Pisano
authors.forename: M G
authors.initials: MG
authors.lastname: Hegazy
authors.forename: E M
authors.initials: EM
authors.lastname: Reimann
authors.forename: L A
authors.initials: LA
authors.lastname: Dokas
mesh_terms: D000818:Animals; D047388:Casein Kinases; D002540:Cerebral Cortex / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D019922:GAP-43 Protein; D008565:Membrane Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010449:Peptide Mapping; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism
chemical_list: D019922:GAP-43 Protein; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011494:Protein Kinases; D047388:Casein Kinases; D014357:Trypsin