Peptidyl-prolyl cis-trans isomerase is the cyclosporin A-binding protein cyclophilin

Nature. 1989 Feb 2;337(6206):473-5. doi: 10.1038/337473a0.


Peptidyl-prolyl cis-trans isomerase (PPIase) catalyses the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and has been shown to accelerate the refolding of several proteins in vitro. Its activity has been detected in yeast, insects and Escherichia coli as well as in mammals, and it is though to be essential for protein folding during protein synthesis in the cell. We purified PPIase from pig kidney and found that its amino-acid sequence is identical to that reported for bovine cyclophilin, a protein known to bind the immunosuppressive drug, cyclosporin A (ref. 5). To investigate the functional relationship between PPIase and cyclophilin we examined the effect of cyclosporin A on PPIase activity and found that it was inhibitory. Thus we propose that the peptidyl-prolyl cis-trans isomerizing activity of PPIase may be involved in events, such as those occurring early in T-cell activation, that are suppressed by cyclosporin A.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Isomerases* / antagonists & inhibitors
  • Amino Acid Isomerases* / metabolism
  • Amino Acid Sequence
  • Animals
  • Carrier Proteins* / metabolism
  • Cattle
  • Cyclosporins / metabolism
  • Cyclosporins / pharmacology
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • Kidney / enzymology
  • Lymphocyte Activation
  • Molecular Sequence Data
  • Molecular Weight
  • Peptidylprolyl Isomerase
  • Rats
  • Sequence Homology, Nucleic Acid
  • Swine
  • T-Lymphocytes / immunology


  • Carrier Proteins
  • Cyclosporins
  • Amino Acid Isomerases
  • Peptidylprolyl Isomerase