title: The 87-kDa protein, a major specific substrate for protein kinase C: purification from bovine brain and characterization.
abstract: The 87-kDa protein, a major specific substrate for protein kinase C, has been purified 500-fold to apparent homogeneity from bovine forebrain supernatant. The purification procedure included batch adsorption to DE-52 (DEAE-cellulose), (NH4)2SO4 precipitation, and chromatography on DEAE-Sephacel, Bio-Gel HTP (hydroxylapatite), Sephacryl S-400, and fast protein liquid chromatography ProRPC. The amino acid composition was notable for its high proportion of alanine (28.6 mol%) and its enrichment in glutamate/glutamine (18.1 mol%), glycine (12.6 mol%), and proline (11.3 mol%). The partial specific volume was 0.702 ml/g; the Stokes radius and sedimentation coefficient were 85 A and 2.11 S, respectively. Although the relative molecular mass of the protein on NaDodSO4/8% PAGE was 87-90 kDa, the molecular mass as determined from the above values was 68 kDa. The frictional ratio was 3.2, and the axial ratio was 60, indicating that the 87-kDa protein is an extremely elongated monomer. The purified 87-kDa protein was phosphorylated by purified protein kinase C to a stoichiometry of 2.2 mol of 32P per mol of 87-kDa protein (calculated using a value of 68 kDa for the molecular mass). Phosphorylation was exclusively on serine residues.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000302:isolation & purification* / Q000378:metabolism; D010750:Phosphoproteins; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; C053933:brain protein 87-kDa, Bos taurus; D011493:Protein Kinase C