| 摘要 |
The cloning and characterization of a new binding protein class, cyclophilin C (cyp C) and homologous proteins, is provided which is capable of binding to, e.g., the immunosuppressive drug cyclosporin A (CsA). The pattern of cyp C mRNA expression differs from that of cyp A mRNA expression, with cyp C being expressed in a more restricted subset of tissues, including those tissues reported to be most affected by CsA therapy. A fusion protein containing, e.g., amino acids 16-212 of cyp C has peptidyl-prolyl-isomerase activity (PPIase), and CsA inhibits this activity. Most significantly, these cyp C fusion proteins can be used as ligands for the identification of intracellular proteins which together form high affinity associations. For example, the cyp C fusion protein binds specifically to a protein of 77 Kd in the absence of CsA, while in the presence of CsA it no longer binds to this p77, but instead binds specifically to a protein 55 Kd, identified as calcineurin. |
