Amino acid sequence of the beta subunit of bovine lung casein kinase II.

The amino acid sequence of the 209-residue beta subunit of bovine lung casein kinase II has been determined. Excluding the amino-terminal blocking group, which was not identified, the molecular weight of the polypeptide chain is 24,239. A marked polarity of the beta subunit is indicated by clusters of negative charges in the amino-terminal region and of positive charges in the carboxyl-terminal region. Whereas the beta subunit shows no homology with any known protein, a segment of the sequence of the larger and microheterogeneous alpha subunit exhibits homology with the catalytic domains of other protein kinases, particularly with the yeast cell-division-control protein CDC28.