Human Creatine Kinase, M subunit (CK-MM, CK-MB) is an enzyme expressed by various tissues and cell types. It catalyses the conversion of creatine and utilizes ATP to produce phosphocreatine (PCr) and adenosine diphosphate (ADP). Cytosolic CK consist of two subunits, which can be either B (brain type) or M (muscle type).
