CKMT1A belongs to the ATP:guanido phosphotransferase family. It contains 1 phosphagen kinase C-terminal domain and 1 phosphagen kinase N-terminal domain. CKMT1A gene is one of two genes which encode the ubiquitous mitochondrial creatine kinase (CKMT1). CKMT1 is responsible for the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine. It belongs to the creatine kinase isoenzyme family. It exists as two isoenzymes, sarcomeric MtCK (CKMT2) and ubiquitous MtCK, encoded by separate genes. CKMT1 occurs in two different oligomeric forms: dimers and octamers, in contrast to the exclusively dimeric cytosolic creatine kinase isoenzymes. Ubiquitous mitochondrial creatine kinase has 8% homology with the coding exons of sarcomeric CKMT1.