Peptidylprolyl isomerase D (cyclophilin D), also known as PPID, is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 which in humans is encoded by the PPID gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

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Function

The protein encoded by this gene is a member of the peptidyl-prolyl cis-trans isomerase (PPIase

Prolyl isomerase

Prolyl isomerase is an enzyme found in both prokaryotes and eukaryotes that interconverts the cis and trans isomers of peptide bonds with the amino acid proline. Proline has an unusually conformationally restrained peptide bond due to its cyclic structure with its side chain bonded to its...

) family. PPIases catalyze the cis-trans isomerization of proline

Proline

Proline is an α-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that the human body can synthesize it. It is unique among the 20 protein-forming amino acids in that the α-amino group is secondary...

 imidic peptide bonds in oligopeptide

Oligopeptide

An oligopeptide consists of between 2 and 20 amino acids and includes dipeptides, tripeptides, tetrapeptides, pentapeptides, etc.Examples of oligopeptides include:...

s and accelerate the folding

Protein folding

Protein folding is the process by which a protein structure assumes its functional shape or conformation. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil....

 of proteins. This protein has been shown to possess PPIase activity and, similar to other family members, can bind to the immunosuppressant

Immunosuppressant

An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...

 ciclosporin

Ciclosporin

Ciclosporin , cyclosporine , cyclosporin , or cyclosporin A is an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the immune system, and therefore the risk of organ rejection...

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Further reading