title: Partial characterization of a 52 kDa CsA/FK506/rapamycin binding protein.
abstract: Identification and characterization of the cellular proteins that specifically bind to the immunosuppressive drugs, cyclosporine (CsA), FK506, and rapamycin is necessary to understand their mechanism of action. We have isolated and partially characterized a 52 kDa binding protein (BP) from calf thymus. Using 12 peptide substrates we observed very low or no cis-trans peptidyl prolyl isomerase activity. We further tested the protein for catalytic activity including kinase activity, phosphatase activity, protein kinase C regulation, and LCK tyrosine kinase regulation. The 52 kDa BP was capable of blocking the cyclic AMP dependent, protein kinase mediated, phosphorylation of histones and casein. The protein did not demonstrate kinase activity, nor did it affect the activity of protein kinase C or LCK tyrosine kinase. Microsequencing of the 52 kDa BP was performed. A comparison of known sequences indicated that the protein is unique and has not been previously characterized.
authors.affiliation: Institute for Biomolecular Studies, Catholic University of America, Washington, DC.
authors.forename: J G
authors.initials: JG
authors.lastname: Donnelly
authors.forename: S J
authors.initials: SJ
authors.lastname: Soldin
mesh_terms: D000591:Amino Acid Isomerases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002417:Cattle; D016572:Cyclosporine / Q000737:chemistry* / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000302:isolation & purification; D007166:Immunosuppressive Agents / Q000737:chemistry* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011090:Polyenes / Q000737:chemistry* / Q000302:isolation & purification; D011494:Protein Kinases / Q000378:metabolism; D020123:Sirolimus; D013379:Substrate Specificity; D016559:Tacrolimus / Q000737:chemistry* / Q000302:isolation & purification; D022021:Tacrolimus Binding Proteins; D013950:Thymus Gland / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D007166:Immunosuppressive Agents; D010446:Peptide Fragments; D011090:Polyenes; D016572:Cyclosporine; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D000591:Amino Acid Isomerases; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus; D016559:Tacrolimus