CKB(Creatine kinase B type) contains 1 phosphagen kinase C-terminal domain and 1 phosphagen kinase N-terminal domain. It belongs to the ATP:guanido phosphotransferase family. CKB consists of a homodimer of two identical brain-type CK-B subunits. CKB is a cytoplasmic enzyme involved in cellular energy homeostasis, with certain fractions of the enzyme being bound to cell membranes, ATPases, and a variety of ATP-requiring enzymes in the cell. There, CKB forms tightly coupled microcompartments for in situ regeneration of ATP that has been used up. CKB reversibly catalyzes the transfer of "energy-rich" phosphate between ATP and creatine or between phospho-creatine (PCr) and ADP. Its functional entity is a homodimer in brain, smooth muscle as well as in other tissues and cells such as neuronal cells, retina, kidney, bone etc.

≥ 90% as determined by SDS-PAGE.