TISSUE DISTRIBUTION AND ABUNDANCE OF HUMAN FKBP51, AN FK506-BINDING PROTEIN THAT CAN MEDIATE CALCINEURIN INHIBITION

We previously described the isolation of an FK506-binding protein, FKB P51, that is predominantly expressed in murine T cells and is capable of mediating drug-dependent calcineurin inhibition in vitro. In additi on, the gene for FKBP51 is induced by glucocorticoids. Screening of a human thymus cDNA library resulted in the identification of the human homologue of FKBP51. Expression of the 3.7 kb mRNA corresponding to FK BP51 is induced by glucocorticoids in the human T cell line, C7TK.4. T he 51.2 kDa protein encoded by this gene shares 87% identity to murine FKBP51 and demonstrates a similar IC50 value for the FK506-mediated i nhibition of calcineurin phosphatase in vitro. The distribution and ab undance of FKBP51 and FKBP12 in seventeen human tissues were compared by Western analysis. Unlike its murine counterpart, the human FKBP51 i s abundantly expressed in numer ous tissues and in many cases, is in m olar excess over FKBP12. (C) 1997 Academic Press.