RAPIDLY PHOSPHORYLATED HISTONE-LIKE PROTEINS ARE MODULATED IN THE COURSE OF TRANSCRIPTION BLOCK BY 5,6-DICHLORO-1-BETA-D-RIBOFURANOSYLBENZIMIDAZOLE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 31  (2) , 354-359
Abstract
Putative histone H2A and H4 proteins with posttranslationally added and covalently linked phosphate group(s) were found in salivary gland cells of Chironomus tentans. The phosphate moieties possess a rapid turnover rate and the incorporation of 32P reaches steady-state level within 5-10 min of incubation. The H2A-like protein incorporates twice as much label as the H4-like one. The core histones H2B and H3 are not measurably phosphorylated under identical experimental conditions. The administration of the nucleoside analog 5,6-dichloro-1-.beta.-D-ribofuranosylbenzimidazole (DRB), a likely inhibitor of transcription initiation, rapidly modulates the phosphorylation of H2A- and H4-like proteins. The incorporation of 32P into the H2A-like phosphoprotein is enhanced by up to 180% after 3-10 min of preincubation with DRB but the rise in phosphorylation is of a transient character. The phosphorylation of H4-like protein is affected somewhat later than that of H2A but the stimulatory effect persists even after a longer pretreatment with DRB. If the elongation inhibitor .alpha.-amanitin replaces DRB in similar experiments no significant effect on histone phosphorylation can be registered. The results are discussed in relation to the possibilities that there is a cause and effect relation between the rapid modulation of phosphorylated putative histone proteins and the repression of gene activity or condensation of active chromatin.

This publication has 1 reference indexed in Scilit: