Prolyl Isomerases

Prolyl isomerases, such as the cyclophilins and FK506 binding proteins, are ubiquitous proteins, which are found in all organisms and all cellular compartments. In bacteria a prolyl isomerase is associated with the ribosome. Prolyl isomerases, such as the cyclophilins and FK506 binding proteins, are ubiquitous proteins, which are found in all organisms and all cellular compartments. In bacteria a prolyl isomerase is associated with the ribosome. The functions of prolyl isomerases in the cell are not confined to accelerating protein folding. Prolyl isomerases belong to three structurally diverse families: the cyclophilins, the FK506 binding proteins, and the parvulins. Usually, these Prolyl isomerases are abbreviated to Cyp, FKBP and Parv, followed by the molecular mass and, sometimes, an indicator for the subcellular localization. Cyp18cy thus denotes the cytoplasmic cyclophilin with a molecular mass of 18 kDa. This cyclophilin is also often referred to as CypA. The prolyl isomerases catalyze isomerizations only at prolyl bonds and not at nonprolyl peptide bonds.