NAP-2: Histone chaperone function and phosphorylation state through the cell cycle

被引:57
作者
Rodriguez, P
Pelletier, J
Price, GB
Zannis-Hadjopoulos, M
机构
[1] McGill Univ, Ctr Canc, Montreal, PQ H3G 1Y6, Canada
[2] McGill Univ, Dept Biochem, Montreal, PQ H3G 1Y6, Canada
基金
英国医学研究理事会;
关键词
casein kinase II; cell cycle; histone chaperone; nucleosome assembly protein; phosphorylation;
D O I
10.1006/jmbi.2000.3674
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
We have recently cloned the human nucleosome assembly protein 2 (NAP-2). Here, we demonstrate that casein kinase 2 (CKII) from HeLa cell nuclear extracts interacts with immobilized NAP-II, and phosphorylates both NAP-2 and nucleosome assembly protein 1 (NAP-1) in vitro. Furthermore, NAP-1 and NAP-2 phosphorylation in crude HeLa cell extracts is abolished by heparin, a specific inhibitor of CKII. Addition of core histones can stimulate phosphorylation of NAP-1 and NAP-2 by CKII. NAP-2 is also a phosphoprotein in vivo. The protein is phosphorylated at the G0/G1 boundary but it is not phosphorylated in S-phase. Here, we show that NAP-2 is a histone chaperone throughout the cell cycle and that its cell-cycle distribution might be governed by its phosphorylation status. Phosphorylated NAP-2 remains in the cytoplasm in a complex with histones during the G0/G1 transition, whereas its dephosphorylation triggers its transport into the nucleus, at the G1/S-boundary, with the histone cargo, suggesting that binding to histones does not depend on phosphorylation status. Finally, indirect immunofluorescence shows that NAP-2 is present during metaphase of HeLa and COS cells, and its localization is distinct from metaphase chromosomes. (C) 2000 Academic Press.
引用
收藏
页码:225 / 238
页数:14
相关论文
共 44 条