Histone H1 kinase from mouse plasmacytoma. Further characterization and molecular structure.

A cAMP-independent protein kinase which phosphorylates histone H1 to a high level and which may correspond to the mitotic H1 kinase has been partially purified and characterized from mouse plasmacytoma microsomes [Quirin-Stricker, C., and Schmitt, M. (1981) Eur. J. Biochem. 118, 165-172]. The present study compares the microsome-associated and the chromatin-associated histone H1 kinases isolated from mouse plasmacytoma cells. The results indicate that the two H1 kinases are indistinguishable by several criteria. The molecular structure of the microsome-associated histone H1 kinase has been determined (a) by exclusion chromatography on Ultrogel, (b) by electrophoresis in non-denaturing polyacrylamide gels of graded porosity and (c) by sodium dodecyl sulfate/polyacrylamide gel electrophoresis of the H1 kinase activity peak from an AcA-34 Ultrogel column. All these techniques gave the same result: H1 kinase may exist in a native form as a monomeric enzyme with an apparent relative molecular mass of 90 000 +/- 8000.