Abstract
Histone phosphokinase activity is present in nucleoli and chromatin isolated from nuclei of rat ventral prostate. The activity (utilizing lysine-rich histone as substrate) in each of these subnuclear fractions is maximal at pH 8.0-8.2, is optimally stimulated in the presence of dithiothreitol and NaCl, and requires Mg2+. Enzymic properties described for the histone phosphokinase activities are similar for nucleolus and chromatin, but are different from those demonstrated by kinases which readily phosphorylate phosvitin. Histone phosphokinase activity of the nucleolus declines about 18% at 24 h and 45% at 48 h post orchiectomy. This decrease in activity is prevented by testosterone replacement therapy. Chromatin-associated histone phosphokinase activity also declines following orchiectomy (21% at 48 h and 66% by 96 h). Thus, the rates of decline of nueleolar and chromatin-associated histone phosphokinase activity in orchiectomized rats described here are slower compared to the enzymic activity toward acidic protein substrates. This further suggests that changes in androgenic status results in differential effects on the protein phosphokinase reactions associated with the prostatic nucleus.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 151-157 |
| Number of pages | 7 |
| Journal | Experimental Cell Research |
| Volume | 106 |
| Issue number | 1 |
| DOIs | |
| State | Published - Apr 1977 |
Bibliographical note
Funding Information:The authors wish to acknowledge the excellent assistance of Mr Alan T. Davis durine these exoeri-ments. This work was supportedi n p&t by Research Grant No. CA15062 from NCI. NIH. USPHS and grant SMF 171-76 from the Minnesota Medical Foundation.