title: Expression and characterization of human FKBP52, an immunophilin that associates with the 90-kDa heat shock protein and is a component of steroid receptor complexes.
abstract: Using an FK506 affinity column to identify mammalian immunosuppressant-binding proteins, we identified an immunophilin with an apparent M(r) approximately 55,000, which we have named FKBP52. We used chemically determined peptide sequence and a computerized algorithm to search GenPept, the translated GenBank data base, and identified two cDNAs likely to encode the murine FKBP52 homolog. We amplified a murine cDNA fragment, used it to select a human FKBP52 (hFKBP52) cDNA clone, and then used the clone to deduce the hFKBP52 sequence (calculated M(r) 51,810) and to express hFKBP52 in Escherichia coli. Recombinant hFKBP52 has peptidyl-prolyl cis-trans isomerase activity that is inhibited by FK506 and rapamycin and an FKBP12-like consensus sequence that probably defines the immunosuppressant-binding site. FKBP52 is apparently common to several vertebrate species and associates with the 90-kDa heat shock protein (hsp90) in untransformed mammalian steroid receptor complexes. The putative immunosuppressant-binding site is probably distinct from the hsp90-binding site, and we predict that FKBP52 has different structural domains to accommodate these functions. hFKBP52 contains 12 protein kinase phosphorylation-site motifs and a potential calmodulin-binding site, implying that posttranslational phosphorylation could generate multiple isoforms of the protein and that calmodulin and intracellular Ca2+ levels could affect FKBP52 function. FKBP52 transcripts are present in a variety of human tissues and could vary in abundance and/or stability.
mesh_terms: D000591:Amino Acid Isomerases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D019696:Peptidylprolyl Isomerase; D015347:RNA Probes; D011987:Receptors, Steroid / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D016559:Tacrolimus / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D015347:RNA Probes; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase; D016559:Tacrolimus