A Xenopus laevis creatine kinase isozyme (CK-III/III) expressed preferentially in larval striated muscle: cDNA sequence, developmental expression and subcellular immunolocalization.

A cDNA containing the nearly complete coding sequence of CK-III subunit of X. laevis was isolated, sequenced and further identified by comparing the tissue distribution of CK-III/III isozyme with that of its messenger. Comparison of CK-III deduced amino acid sequence with other CK sequences published reveals its close homology to M-CK subunits. Results using both cDNA probes and monoclonal antibodies specific for CK-III subunits indicate that the appearance and the accumulation of CK-III occur in parallel with myoblast differentiation. Moreover, subcellular immuno-histolocalization shows that CK-III/III isozyme is especially concentrated on larval myofibres at the level of A-bands.