FKBP54, a novel FK506-binding protein in avian progesterone receptor complexes and HeLa extracts
Avian progesterone receptor complexes contain five major co-purifying proteins, including hsp90, hsp70, and a 23-kDa protein. The other receptor-associated proteins, p50 and p54, share amino acid sequence similarities with a 52-59-kDa component (p59, hsp56, or FKBP52) of mammalian steroid receptor c...
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Published in | The Journal of biological chemistry Vol. 268; no. 32; pp. 24270 - 24273 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Biochemistry and Molecular Biology
15.11.1993
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Subjects | |
Online Access | Get full text |
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Summary: | Avian progesterone receptor complexes contain five major co-purifying proteins, including hsp90, hsp70, and a 23-kDa protein.
The other receptor-associated proteins, p50 and p54, share amino acid sequence similarities with a 52-59-kDa component (p59,
hsp56, or FKBP52) of mammalian steroid receptor complexes that is also a member of the FK506-binding proteins (FKBP) family
of immunophilins. We show here that p50, but not p54, cross-reacts with a rabbit antiserum prepared against human FKBP52.
Both p50 and p54 bind an FK506 affinity resin at 0.5 M KCl, but only p50 binds efficiently in low salt conditions. Glycerol
density gradient analyses show that both p50 and p54 exist predominantly in oligomeric complexes at low ionic strength. The
poor retention of p54 on FK506 resin at low ionic strength compared with the high retention of p50 suggests that these proteins
may largely exist in separate complexes and may interact with other proteins, such as progesterone receptor, in distinctive
manners. In HeLa cell extracts, a 55-kDa FK506-binding protein, distinct from FKBP52, cross-reacts with anti-p54 antibody
FF1. We conclude that p50 is avian FKBP52, whereas p54 and the 55-kDa human FF1 antigen are FKBP54, a novel immunophilin. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(20)80520-1 |