CKMT2 is a protein-coding gene that encodes for the mitochondrial creatine kinase enzyme. This enzyme exists in two isoenzymes: sarcomeric MtCK and ubiquitous MtCK, which are encoded by separate genes . The sarcomeric mitochondrial creatine kinase has approximately 80% homology with the coding exons of ubiquitous mitochondrial creatine kinase .
The enzyme occurs in two different oligomeric forms: dimers and octamers, in contrast to the exclusively dimeric cytosolic creatine kinase isoenzymes . CKMT2 is responsible for the transfer of high-energy phosphate from mitochondria to the cytosolic carrier, creatine, which is essential for energy transduction in tissues with large, fluctuating energy demands, such as skeletal muscle, heart, brain, and spermatozoa .
The CKMT2 gene is located on chromosome 5 and has several aliases, including SMTCK, S-MtCK, and Mib-CK . The gene contains sequences homologous to several motifs shared among some nuclear genes encoding mitochondrial proteins, which may be essential for the coordinated activation of these genes during mitochondrial biogenesis .
The recombinant human CKMT2 protein is often produced with a His-tag and corresponds to the amino acids 40-419 of the human CKMT2 . It is typically expressed in E. coli and purified to a high degree of purity, often exceeding 90% as determined by SDS-PAGE .
CKMT2 plays a central role in energy homeostasis by catalyzing the reversible transfer of phosphate between ATP and creatine phosphate . This process is vital for maintaining energy balance in cells, particularly in tissues with high and fluctuating energy demands. The enzyme’s activity is crucial for the proper functioning of skeletal muscle, heart, brain, and spermatozoa .
Mutations or dysregulation of the CKMT2 gene have been associated with various diseases, including simple partial epilepsy and Klebsiella pneumonia . The enzyme’s role in energy metabolism also makes it a potential target for therapeutic interventions in conditions related to energy homeostasis and mitochondrial function.