Creatine kinase, muscle also known as CKM is a creatine kinase that in humans is encoded by the CKM gene. In the figure to the right, the crystal structure of the muscle-type M-CK monomer is shown. In vivo, two such monomers arrange symmetrically to form the active MM-CK enzyme. In heart, in addition to the MM-CK homodimer, also the heterodimer MB-CK consisting of one muscle (M-CK) and one brain-type (B-CK) subunit is expressed. The latter may be an important serum marker for myocardial infarction, if released from damaged myocardial cells into the blood where it can be detected by clinical chemistry.
