α-1,2,3,4,5,6-Hexachlorocyclohexane (α-HCH) is known to induce mixed-function oxidases in rat liven endoplasmic reticulum and to stimulate liver cell proliferation. During the 12 hr after administration of α-HCH the phosphorylation of nuclear acidic proteins in vivo increased to about twice the control level. Essentially all of the increased phosphorylation after α-HCH in vivo involved preferential 32P incorporation into fractions of phenol-solublel acidic chromatin proteins, resolved by polyacrylamide gel electrophoresis into proteins with estimated molecular weights of 15,000-25,000, 35,000-50,000, and 60,000-90,000. Although no qualitative changes in the electrophoretograms of phenol-soluble acidic chromatin proteins were observed, the incorportation of radioactive amino acids into the acidic protein fraction of rat liver nuclei in vivo increased 6 hr after α-HCH, suggesting a change in turnover or an increased number of phosphate acceptor sites at the time of maximal phosphorylation of acidic nuclear phosphoproteins.
ACKNOWLEDGMENTS The authors are indebted to Mrs. Catherine Craddock and Mr. Augustus White for their excellent technical assistance.
- Copyright ©, 1974, by Academic Press, Inc.