Cyclophilin

Cyclophilin type peptidyl-prolyl cis-trans isomerase/CLD
Ribbon diagram of cyclophilin A in complex with ciclosporin (yellow). From PDB: 1CWA​.
Identifiers
Symbol	Pro_isomerase
Pfam	PF00160
Pfam clan	CL0475
InterPro	IPR002130
PROSITE	PDOC00154
SCOP2	1cyh / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Cyclophilins (CYPs) are a family of proteins named after their ability to bind to ciclosporin (cyclosporin A), an immunosuppressant which is usually used to suppress rejection after internal organ transplants.^[1] They are found in all domains of life. These proteins have peptidyl prolyl isomerase activity, which catalyzes the isomerization of peptide bonds from trans form to cis form at proline residues and facilitates protein folding.

Cyclophilin A is a cytosolic and highly abundant protein. The protein belongs to a family of isozymes, including cyclophilins B and C, and natural killer cell cyclophilin-related protein.^[2][3][4] Major isoforms have been found within single cells, including inside the Endoplasmic reticulum, and some are even secreted.