Kuang J, Penkala J E, Wright D A, Saunders G F, Rao P N
Department of Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston 77030.
Dev Biol. 1991 Mar;144(1):54-64. doi: 10.1016/0012-1606(91)90478-l.
At the onset of mitosis, eukaryotic cells display an abrupt increase in a Ca2(+)- and cyclic nucleotide-independent histone H1 kinase activity, referred to as growth-associated or M phase-specific H1 kinase. The molecular basis for this activity is generally attributed to a kinase complex that consists of the p34cdc2 protein and cyclin, and exhibits maturation-promoting factor (MPF) activity. In the present study, we show that more than one kinase contributes to M phase-specific H1 kinase activity. When mature Xenopus oocyte extract prepared with ATP gamma S and NaF was fractionated by gel filtration, two prominent peaks of H1 kinase activity were detected, with apparent molecular masses of 600 and 150 kDa. The 150-kDa kinase copurified with the p34cdc2 protein and was immobilized by the suc 1 gene product p13 and anti-cyclin B2, which are specific for the cdc2 kinase complex. However, the 600-kDa kinase did not satisfy any of these criteria, thus identifying it as a novel M phase-specific H1 kinase. Only the 600-kDa kinase was recognized by the mitosis-specific monoclonal antibody, MPM-2, which inhibits Xenopus oocyte maturation and immunodepletes MPF activity. Furthermore, not only did the full activation of this kinase (MPM-2 kinase) coincide with the activation of MPF during the cell cycle, but also MPM-2 kinase-positive fractions obtained by gel filtration accelerated progesterone-induced oocyte maturation. It is, therefore, likely that MPM-2 kinase is a positive regulator in the M phase induction pathway.
在有丝分裂开始时，真核细胞中一种与Ca2+和环核苷酸无关的组蛋白H1激酶活性会突然增加，这种激酶被称为生长相关或M期特异性H1激酶。这种活性的分子基础通常归因于一种由p34cdc2蛋白和细胞周期蛋白组成的激酶复合物，它具有促成熟因子（MPF）活性。在本研究中，我们发现不止一种激酶对M期特异性H1激酶活性有贡献。当用ATPγS和NaF制备的成熟非洲爪蟾卵母细胞提取物通过凝胶过滤进行分级分离时，检测到两个明显的H1激酶活性峰，其表观分子量分别为600 kDa和150 kDa。150 kDa的激酶与p34cdc2蛋白共纯化，并被suc 1基因产物p13和抗细胞周期蛋白B2固定，它们对cdc2激酶复合物具有特异性。然而，600 kDa的激酶不符合这些标准中的任何一条，因此将其鉴定为一种新型的M期特异性H1激酶。只有600 kDa的激酶能被有丝分裂特异性单克隆抗体MPM-2识别，该抗体可抑制非洲爪蟾卵母细胞成熟并免疫耗尽MPF活性。此外，这种激酶（MPM-2激酶）的完全激活不仅与细胞周期中MPF的激活同时发生，而且通过凝胶过滤获得的MPM-2激酶阳性组分还能加速孕酮诱导的卵母细胞成熟。因此，MPM-2激酶很可能是M期诱导途径中的一种正调控因子。
