Reversibly catalyzes the transfer of phosphate between ATP and various phosphogens (e.g. creatine phosphate). Creatine kinase isoenzymes play a central role in energy transduction in tissues with large, fluctuating energy demands, such as skeletal muscle, heart, brain and spermatozoa.
Belongs to the ATP:guanido phosphotransferase family. Contains 1 phosphagen kinase C-terminal domain. Contains 1 phosphagen kinase N-terminal domain.