Partial characterization of a 52 kDa CsA/FK506/rapamycin binding protein

✍ Scribed by James G. Donnelly; Steven J. Soldin

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 817 KB
• Volume: 27
• Category: Article
• ISSN: 0009-9120
• DOI: 10.1016/0009-9120(94)90040-x

✦ Synopsis

Identification and characterization of the cellular proteins that specifically bind to the immunosupprassive drugs, cyclosporine (CsA), FKS06, 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 catab/tic activity including kinase activity, phosphatase activity, protein kinase C regulation, and LCK tyrosine kinase regulation. The 52 kOa BP was capable of blocking the cyclic AMP dependent, protein kinase mediated, phosphorylation of histonas and casein. The protein did not demonstrate klnase activity, nor did it affect the activity of protein kinase C or LCK tyrosine kinase. Microsequancing of the 52 kDa BP was performed. A comperison of known sequences indicated that the protein is unique and has not been previously characterized.