Reversibly catalyzes the transfer of phosphate between ATPand various phosphogens (e. g. creatine phosphate). Creatine kinase isoenzymes play a central role in energy transductionin tissues with large, fluctuating energy demands, such as skeletalmuscle, heart, brain and spermatozoa. Acts as a keyregulator of adaptive thermogenesis as part of the futile creatinecycle: localizes to the mitochondria of thermogenic fat cells and actsby mediating phosphorylation of creatine to initiate a futile cycle ofcreatine phosphorylation and dephosphorylation. Duringthe futile creatine cycle, creatine and N-phosphocreatine are in afutile cycle, which dissipates the high energy charge of N-phosphocreatine as heat without performing any mechanical or chemicalwork. [1]

MPFSNSHNALKLRFPAEDEFPDLSAHNNHMAKVLTPELYAELRAKSTPSGFTLDDVIQTGVDNPGHPYIMTVGCVAGDEESYEVFKDLFDPIIEDRHGGYKPSDEHKTDLNPDNLQGGDDLDPNYVLSSRVRTGRSIRGFCLPPHCSRGERRAIEKLAVEALSSLDGDLAGRYYALKSMTEAEQQQLIDDHFLFDKPVSPLLLASGMARDWPDARGIWHNDNKTFLVWVNEEDHLRVISMQKGGNMKEVFTRFCTGLTQIETLFKSKDYEFMWNPHLGYILTCPSNLGTGLRAGVHIKLPNLGKHEKFSEVLKRLRLQKRGTGGVDTAAVGGVFDVSNADRLGFSEVELVQMVVDGVKLLIEMEQRLEQGQAIDDLMPAQK