Cyclophilins are a family of extremely conserved proteins, known as immunophilins. Cyclophilin A (CyPA) is present in all tissues in prokaryotes and eukaryotes. It is present in all organs of human. Cyclophilin A (CyPA), a 20 kDa chaperone protein, that is liberated from vascular smooth muscle cells (VSMCs).

Cyclophilin A human has been used in the study to interpret the mechanisms by which extracellular CyPA initiates endothelial activation.

Cyclophilin A (CyPA) participates in intracellular signalling and protein trafficking. It helps to control other proteins activity. CyPA plays a physiological and pathological role in cardiovascular diseases. Hence it acts as an important biomarker and mediator in several cardiovascular diseases, like vascular stenosis, atherosclerosis and abdominal aortic aneurysms. CyPA can induce the proliferation and inflammatory cell migration of vascular smooth muscle cells (VSMC) in vitro and in vivo.

Cyclophilins are peptidyl prolyl isomerases that catalyze the cis-trans isomerization of X-Pro peptide bonds. They are highly-conserved cytoplasmic enzymes that accelerate protein folding and facilitate HIV infectivity. Cyclosporin A binds to cyclophilin and inhibits its activity. The cyclosporin A-cyclophilin complex binds to calcineurin and inhibits T-cell activation. The structure of human, recombinant cyclophilin is given by Holzman, et al.

Composed of amino acids 1-165 plus an N-terminal 20 amino acid His-tag

Solution in 20mM Tris, pH 8.0, containing 20 mM NaCl, 0.5 mM DTT and 10% glycerol