Cyclophilin-40, a protein with homology to the P59 component of the steroid receptor complex. Cloning of the cDNA and further characterization.
We have reported previously the isolation and preliminary characterization of a 40-kDa cyclosporin A (CsA)-binding protein, cyclophilin-40 (CyP-40). To determine the sequence of this protein, degenerate oligonucleotide primers based on bovine brain CyP-40 tryptic peptides were used to generate a polymerase chain reaction fragment of CyP-40 cDNA. This was used to isolate the complete cDNA from a human pancreatic islet cell library. Northern analysis indicated ubiquitous distribution of CyP-40 mRNA throughout human tissues. The CyP-18 domain of CyP-40 is most similar to maize CyP (64.3% identity), whereas 150 amino acids of the non-CyP-18 domain of CyP-40 share 30.7% identity with P59, a member of the steroid receptor complex. Failure to detect glycosylation and mass spectroscopy with isolated CyP-40 indicate minimal, if any, posttranslational modification. Employing a new assay for calcineurin protein phosphatase activity to compare the effects of CyP-40.CsA and CyP-18.CsA complexes, IC50 values of 320 nM +/- 20 and 195 nM +/- 15, respectively, were obtained. A chemical cross-linking study revealed that CyP-40 competes for 125I-CyP-18 binding to calcineurin in the presence of CsA. The homology of CyP-40 to P59 suggests that CyP-40 might be involved in modulating the activity of biologically important receptors.
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
L J
LJ
Kieffer
T W
TW
Seng
W
W
Li
D G
DG
Osterman
R E
RE
Handschumacher
R M
RM
Bayney
D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics; D002417:Cattle; D003001:Cloning, Molecular; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins; D016572:Cyclosporine / Q000378:metabolism; D004247:DNA; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010179:Pancreas / Q000378:metabolism; D019696:Peptidylprolyl Isomerase; D011987:Receptors, Steroid / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D000081406:Peptidyl-Prolyl Isomerase F; D009838:Oligodeoxyribonucleotides; D011987:Receptors, Steroid; D016572:Cyclosporine; D004247:DNA; D000591:Amino Acid Isomerases; D021983:Cyclophilins; D019696:Peptidylprolyl Isomerase