Stimulation of a Ca(2+)-calmodulin-activated histone 3 arginine kinase in quiescent rat heart endothelial cells compared to actively dividing cells

A Ca(2+)-calmodulin-activated histone 3 kinase was partially purified from nuclear extracts of dividing and quiescent rat heart endothelial cells. The histone 3 phosphorylating activity was 20-100-fold higher in quiescent than in dividing cells. Base hydrolysis followed by amino acid analysis reveal...

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Bibliographic Details
Published in:	The Journal of biological chemistry 1995-09, Vol.270 (39), p.23155-23158
Main Authors:	Wakim, B T, Grutkoski, P S, Vaughan, A T, Engelmann, G L
Format:	Article
Language:	eng
Subjects:	Animals Arginine - analogs & derivatives Arginine - analysis Blotting, Western Calcium-Calmodulin-Dependent Protein Kinases - isolation & purification Calcium-Calmodulin-Dependent Protein Kinases - metabolism Cell Division Cell Nucleus - enzymology Cells, Cultured Chromatography, High Pressure Liquid Endothelium, Vascular - cytology Endothelium, Vascular - enzymology Heart Histones - metabolism Organophosphorus Compounds - analysis Rats Substrate Specificity
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Summary:	A Ca(2+)-calmodulin-activated histone 3 kinase was partially purified from nuclear extracts of dividing and quiescent rat heart endothelial cells. The histone 3 phosphorylating activity was 20-100-fold higher in quiescent than in dividing cells. Base hydrolysis followed by amino acid analysis revealed that histone 3 was phosphorylated on arginine. Further investigations were conducted to determine whether phosphorylation of histone 3 also occurred in vivo. Cells were incubated for 3 h in a phosphate-free medium supplemented with [32P]phosphoric acid. It was observed that the nuclear content of arginine-phosphorylated histone 3 was considerably higher in quiescent than in dividing rat heart endothelial cells. The histone 3 arginine kinase is a component of a complex containing a Ca(2+)-dependent calmodulin-binding protein of apparent molecular mass of 85 kDa. Using polyclonal antibodies to an 85-kDa protein, also the major Ca(2+)-dependent calmodulin-binding component of the histone 3 arginine kinase from calf thymus, an immunoreactive protein of identical apparent molecular mass was found to be present in equal amounts both in dividing and quiescent cells. We propose that the 85-kDa protein is either the histone 3 arginine kinase or one of its subunits and that phosphorylation of histone 3 is involved with cell cycle exit in eukaryotes.
ISSN:	0021-9258 1083-351X