Kurn N, Sela B A
Eur J Biochem. 1981 Dec;121(1):53-7. doi: 10.1111/j.1432-1033.1981.tb06428.x.
Genetically altered calmodulin activity in spontaneously derived mutant strains, which were selected for resistance to the toxic effect of a specific inhibitor, the phenothiazine drug fluphenazine, is demonstrated. Partially purified calmodulin preparations from wild-type and fluphenazine-resistant strains of the multicellular alga Volvox carteri, were tested for the ability to activate Ca2+-ATPase of the erythrocyte membranes, and the inhibition of this stimulatory activity by fluphenazine. Unlike the preparation obtained from wild-type cells, mutant calmodulin is shown to be insensitive to fluphenazine inhibition, in one case, and calmodulin from another strain was found to be inactive in vitro, i.e. it did not activate Ca2+-ATPase. The pleiotropic phenotype of the spontaneously derived mutant strains involved aberrant multicellular organization and hormone-independent commitment of the multipotent asexual reproductive cells, gonodia, to sexual development. These results clearly implicate calmodulin in the control of development and morphogenesis in this simple multicellular eukaryote. In addition, intracellular inhibition of calmodulin in wild-type cells is shown to block the morphogenic process of embryo inversion and to arrest motility. The availability of mutant calmodulin will facilitate further investigation of the role of this ubiquitous regulatory protein in the control of development and differentiation in multicellular eukarytes, as well as the fine structure/function relationship with regard to calmodulin modulation of a wide variety of cellular processes.
研究表明，在自发衍生的突变菌株中，钙调蛋白活性发生了基因改变，这些突变菌株是通过对特定抑制剂（吩噻嗪类药物氟奋乃静）的毒性作用产生抗性而筛选出来的。对多细胞藻类卡特氏团藻野生型和氟奋乃静抗性菌株的部分纯化钙调蛋白制剂，测试了其激活红细胞膜Ca2+-ATP酶的能力以及氟奋乃静对这种刺激活性的抑制作用。与从野生型细胞获得的制剂不同，在一种情况下，突变型钙调蛋白对氟奋乃静抑制不敏感，而从另一个菌株中发现的钙调蛋白在体外无活性，即它不能激活Ca2+-ATP酶。自发衍生的突变菌株的多效表型涉及异常的多细胞组织以及多能无性生殖细胞（生殖细胞）向有性发育的激素非依赖性转变。这些结果清楚地表明钙调蛋白参与了这种简单多细胞真核生物的发育和形态发生控制。此外，野生型细胞中钙调蛋白的细胞内抑制作用被证明会阻断胚胎反转的形态发生过程并使运动停止。突变型钙调蛋白的可得性将有助于进一步研究这种普遍存在的调节蛋白在多细胞真核生物发育和分化控制中的作用，以及与钙调蛋白对多种细胞过程调节相关的精细结构/功能关系。
