A cytosolic binding protein for the immunosuppressant FK506 has peptidyl-prolyl isomerase activity but is distinct from cyclophilin

John J. Siekierka, Shirley H.Y. Hung, Martin Poe, C. Shirley Lin, Nolan H. Sigal

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CYCLOSPORIN A and the newly discovered immunosuppressant, FK-506, are potent inhibitors of T cell activation. In addition to their clinical importance in the prevention of allograft rejection, cyclosporin A and FK-506 represent important reagents for the study of the molecular mechanisms of lymphocyte activation. Cyclosporin A, a cyclic undecapeptide and FK-506, a macrolide, although chemically distinct, inhibit similar lymphocyte activation responses. The earliest responses inhibited in the T cell seem to be the expression of early phase T cell-activation genes for interleukins 2, 3 and 4, granulocyte-macrophage colony stimulating factor and gamma interferon. Although FK-506 and cyclosporin A seem to inhibit similar signal transduction processes, they do so by interacting with distinct cytosolic proteins. We report here the purification to homogeneity of a specific FK-506 binding protein that is distinct from the cyclosporin A-binding protein, cyclophilin. In addition, we show that this FK-506 binding protein, like cyclophilin, has peptidyl-prolyl isomerase activity.

Original languageEnglish
Pages (from-to)755-757
Number of pages3
Issue number6244
StatePublished - 1 Jan 1989


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