Cyclosporine mediates its immunosuppressive effect by preventing the synthesis of lymphokine mRNA during the process of T lymphocyte activation. Although the detailed molecular mechanism by which CsA achieves this effect is unknown, two proteins have been identified as putative intracellular CsA-receptor proteins. One of these, calmodulin, is an important Ca++-binding protein and enzyme cofactor and the other, cyclophilin, is a novel protein that is reported to have protein kinase activity. In this study the CsA-binding capacity of both these proteins has been assessed using CsA-coated ELISA plates and CsA-affinity gel matrices. CsA binding was shown by cyclophilin whereas no CsA-calmodulin binding could be detected under identical conditions. However, it was not possible to demonstrate any cyclophilin-associated protein kinase activity. Jurkat cells were probed for the presence of CsA-binding proteins using the CsA-affinity gel matrix; a 17 KD protein, most probably cyclophilin, was identified as the major CsA-binding protein. In addition, a previously unidentified CsA-binding 45 KD phosphoprotein was precipitated from 32P-labeled Jurkat cells. These results would support cyclophilin as the major, if not only, intracellular receptor protein for CsA. However, the relationship between binding of CsA to cyclophilin and/or the 45 KD phosphoprotein and the immunosuppressive effects of CsA is still unknown.
Cyclosporine mediates its immunosuppressive effect by preventing the synthesis of lymphokine mRNA during the process of T lymphocyte activation . Although the detailed molecular mechanism by which CsA achieves this effect is unknown , two proteins have been identified as putative intracellular CsA - receptor proteins . One of these , calmodulin , is an important Ca++-binding protein and enzyme cofactor and the other , cyclophilin , is a novel protein that is reported to have protein kinase activity . In this study the CsA - binding capacity of both these proteins has been assessed using CsA - coated ELISA plates and CsA - affinity gel matrices . CsA binding was shown by cyclophilin whereas no CsA - calmodulin binding could be detected under identical conditions . However , it was not possible to demonstrate any cyclophilin - associated protein kinase activity . Jurkat cells were probed for the presence of CsA - binding proteins using the CsA - affinity gel matrix ; a 17 KD protein , most probably cyclophilin , was identified as the major CsA - binding protein . In addition , a previously unidentified CsA - binding 45 KD phosphoprotein was precipitated from 32P - labeled Jurkat cells . These results would support cyclophilin as the major , if not only , intracellular receptor protein for CsA. However , the relationship between binding of CsA to cyclophilin and/or the 45 KD phosphoprotein and the immunosuppressive effects of CsA is still unknown .
Which is the receptor for the immunosuppressive drug cyclosporin A (CsA)?
Which is the receptor for the immunosuppressive drug cyclosporin A ( CsA ) ?
cyclophilin
cyclophilin