The Hsp56 component of steroid receptor complexes binds to immobilized FK506 and shows homology to FKBP-12 and FKBP-13

• Published in: The Journal of biological chemistry Vol. 267; no. 5; pp. 2868 - 2871
• Main Authors: A W Yem, A G Tomasselli, R L Heinrikson, H Zurcher-Neely, V A Ruff, R A Johnson, M R Deibel, Jr
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 15-02-1992
• Subjects: Amino Acid Sequence; Animals; binding; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cattle; Cell Line; Chromatography, Affinity; Electrophoresis, Polyacrylamide Gel; Heat-Shock Proteins - genetics; Heat-Shock Proteins - isolation & purification; Heat-Shock Proteins - metabolism; homology; Hsp56 protein; Humans; Jurkat cells; man; Molecular Sequence Data; Molecular Weight; Protein Binding; receptors; Receptors, Steroid - genetics; Receptors, Steroid - metabolism; Sequence Homology, Nucleic Acid; steroids; Tacrolimus - metabolism; Tacrolimus Binding Proteins; Thymus Gland - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)50664-0

Extracts from human Jurkat cells or from calf thymus contain a 60-kDa protein that is bound to immobilized FK506. As expected,
the NH2-terminal sequences of the 60-kDa protein from these two species were found to be nearly the same. We were surprised
to discover, however, that the sequence of the human protein was identical to that of Hsp56, a heat shock protein of unknown
function that has been shown to be a component of several steroid receptor complexes. Further analysis of the calf thymus
protein revealed a peptide with homology to a region near the COOH terminus of both FKBP-12 and FKBP-13. It would appear,
therefore, that this 60-kDa protein, or as we refer to it provisionally, "Hsp56," could have the capacity to bind FK506 directly.
These observations lead us to speculate that "Hsp56" may mediate immunosuppression and inhibition of T-cell proliferation
by FK506 and may do so via a cytosolic signal transduction pathway separate, but not necessarily exclusive, from that of FKBP-12
and FKBP-13.