The expression of creatine kinase isozymes in human cultured cells

The BB isozyme of creatine kinase is consistently present in cultured human fibroblasts and shows great variation in activity in long-term lymphoid lines. One mouse line tested, PG 19, had strong activity, but all other rodent lines tested did not express CK BB. Human and mouse CK BB can be expressed independently of each other in human--rodent somatic cell hybrids. There is some evidence that the structural locus for CK BB may be on chromosome 14, but the involvement of other chromosomes, expecially no.17, cannot be excluded. The MM and MB isozymes of creatine kinase were not seen in any human cultured cells.