J.J. Siekierka, S.H.Y. Hung, M. Poe, C.S. Lin, N.H. Sigal, "A cytosolic binding protein for the immunosuppressant FK-506 has peptidyl-prolyl isomerase activity but is distinct from cyclophilin," Nature, 341, 755-7, 26 October 1989.

John J. Siekierka (Merck Sharp & Dohme Research Laboratories, Rahway, N.J.): "Two clinically important immunosuppressant drugs, cyclosporin A (CsA) and FK-506, are valuable probes for studying the molecular mechanisms of T cell activation. Although chemically unique, both drugs appear to act at a similar cellular site. This results in the inhibition of transcription of a limited number of early T cell activation genes (such as interleukin 2) required for T cell proliferation. We show in our paper that a cytoplasmic receptor for FK-506 possesses peptidyl-prolyl cis-trans isomerase activity (PPIase activity), which is specifically inhibited by FK-506, but not CsA. PPIases catalyze the cis-trans isomerization of peptidyl bonds in proteins and peptides and are believed to play a...

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