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In this paper the authors depleted core histone heterodimers H3-H4 at 90 % from the cytoplasm of Xenopus oocytes. They state that their concentration is in the order of 6 uM.

My question is, are histones found in cytoplasm besides the nucleus location? (ignoring the newly sythesized ones), and if so, is there any known function?

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  • $\begingroup$ I can't access that paper, how did they deplete the histones? Did they use siRNA? $\endgroup$ – user137 Jul 6 '15 at 14:49
  • $\begingroup$ @user137 The experiment was done with cell extracts. Histones were depleted with anti-histone antibodies and Protein A coated beads. $\endgroup$ – canadianer Jul 6 '15 at 16:48
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    $\begingroup$ This is quoted from the paper: The cytoplasm of Xenopus eggs contains a large stockpile of core histones in complex with specific chaperone proteins. Histones H3 and H4 are stored as soluble heterodimers… This paper may also interest you: nrcresearchpress.com/doi/abs/10.1139/o06-082#/doi/abs/10.1139/… $\endgroup$ – canadianer Jul 6 '15 at 16:51
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In early embryogenesis, cell division called cleavage occurs every 30 min and there is no transcriptional activity. Oocytes have accumulated important gene transcripts and synthesize the proteins at right times. However, histone is one of the most abundant proteins and it would be difficult to supply enough histone proteins during early embryogenesis while oocytes translate other gene transcripts regulating differentiation.

This is my speculation, but the article calls cytosolic histones "stockpile". Just in case, I don't mean that I deny some other roles of histones in cytosol if there are any.

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