Satterwhite L L, Lohka M J, Wilson K L, Scherson T Y, Cisek L J, Corden J L, Pollard T D
Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Cell Biol. 1992 Aug;118(3):595-605. doi: 10.1083/jcb.118.3.595.
To understand how cytokinesis is regulated during mitosis, we tested cyclin-p34cdc2 for myosin-II kinase activity, and investigated the mitotic-specific phosphorylation of myosin-II in lysates of Xenopus eggs. Purified cyclin-p34cdc2 phosphorylated the regulatory light chain of cytoplasmic and smooth muscle myosin-II in vitro on serine-1 or serine-2 and threonine-9, sites known to inhibit the actin-activated myosin ATPase activity of smooth muscle and nonmuscle myosin (Nishikawa, M., J. R. Sellers, R. S. Adelstein, and H. Hidaka. 1984. J. Biol. Chem. 259:8808-8814; Bengur, A. R., A. E. Robinson, E. Appella, and J. R. Sellers. 1987. J. Biol. Chem. 262:7613-7617; Ikebe, M., and S. Reardon. 1990. Biochemistry. 29:2713-2720). Serine-1 or -2 of the regulatory light chain of Xenopus cytoplasmic myosin-II was also phosphorylated in Xenopus egg lysates stabilized in metaphase, but not in interphase. Inhibition of myosin-II by cyclin-p34cdc2 during prophase and metaphase could delay cytokinesis until chromosome segregation is initiated and thus determine the timing of cytokinesis relative to earlier events in mitosis.
为了解胞质分裂在有丝分裂过程中是如何被调控的,我们检测了细胞周期蛋白-p34cdc2的肌球蛋白-II激酶活性,并研究了非洲爪蟾卵裂解物中肌球蛋白-II的有丝分裂特异性磷酸化。纯化的细胞周期蛋白-p34cdc2在体外可使细胞质和平滑肌肌球蛋白-II的调节轻链在丝氨酸-1或丝氨酸-2以及苏氨酸-9位点发生磷酸化,这些位点已知可抑制平滑肌和非肌肉肌球蛋白的肌动蛋白激活的肌球蛋白ATP酶活性(西川,M.,J.R.塞勒斯,R.S.阿德尔斯坦和日高秀树。1984年。《生物化学杂志》259:8808-8814;本古尔,A.R.,A.E.罗宾逊,E.阿佩拉和J.R.塞勒斯。1987年。《生物化学杂志》262:7613-7617;池部,M.和S.里尔登。1990年。《生物化学》29:2713-2720)。非洲爪蟾细胞质肌球蛋白-II调节轻链的丝氨酸-1或-2在中期稳定的非洲爪蟾卵裂解物中也发生了磷酸化,但在间期没有。在前期和中期,细胞周期蛋白-p34cdc2对肌球蛋白-II的抑制作用可能会延迟胞质分裂,直到染色体分离开始,从而确定胞质分裂相对于有丝分裂早期事件的时间。