ASSOCIATION OF CALMODULIN AND AN UNCONVENTIONAL MYOSIN WITH THE CONTRACTILE VACUOLE COMPLEX OF DICTYOSTELIUM-DISCOIDEUM
ASSOCIATION OF CALMODULIN AND AN UNCONVENTIONAL MYOSIN WITH THE CONTRACTILE VACUOLE COMPLEX OF DICTYOSTELIUM-DISCOIDEUM
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DOI：
10.1083/jcb.118.2.347
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发表时间：
1992-07-01
影响因子：
7.8
通讯作者：
CLARKE, M
中科院分区：
文献类型：
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作者：
ZHU, QL;CLARKE, M
用钙调素特异性单克隆抗体检测营养盘形骨细胞中钙调素的分布。间接免疫荧光显示，钙调蛋白在相亮空泡周围富集。这些液泡在新萌发（非摄食）和生长细胞中的存在，以及液泡对渗透环境变化的反应，将它们确定为收缩液泡，渗透调节细胞器。没有证据表明钙调蛋白与核内体或溶酶体有关，也没有钙调蛋白沿着细胞骨架细丝富集。当从盘形骨柱细胞中提取的膜在平衡蔗糖密度梯度上分离时，钙调素与碱性磷酸酶（一种可收缩液泡膜的细胞化学标记物）以1.156 g/ml的密度共同分离。几种高分子量钙调素结合蛋白在梯度的同一区域富集。一种钙调素结合多肽（分子量约为150 kD）与棘阿米巴肌球蛋白IC特异性抗血清发生交叉反应。通过间接免疫荧光，该蛋白也在收缩液泡膜上富集。这些结果表明，一种结合钙调素的非常规肌球蛋白与盘状骨的收缩液泡有关；酵母和哺乳动物细胞中的类似蛋白质与囊泡运动有关。
mAbs specific for calmodulin were used to examine the distribution of calmodulin in vegetative Dictyostelium cells. Indirect immunofluorescence indicated that calmodulin was greatly enriched at the periphery of phase lucent vacuoles. The presence of these vacuoles in newly germinated (non-feeding) as well as growing cells, and the response of the vacuoles to changes in the osmotic environment, identified them as contractile vacuoles, osmoregulatory organelles. No evidence was found for an association of calmodulin with endosomes or lysosomes, nor was calmodulin enriched along cytoskeletal filaments. When membranes from Dictyostelium cells were fractionated on equilibrium sucrose density gradients, calmodulin cofractionated with alkaline phosphatase, a cytochemical marker for contractile vacuole membranes, at a density of 1.156 g/ml. Several high molecular weight calmodulin-binding proteins were enriched in the same region of the gradient. Ore of the calmodulin-binding polypeptides (molecular mass approximately 150 kD) cross-reacted with an antiserum specific for Acanthamoeba myosin IC. By indirect immunofluorescence, this protein was also enriched on contractile vacuole membranes. These results suggest that a calmodulin-binding unconventional myosin is associated with contractile vacuoles in Dictyostelium; similar proteins in yeast and mammalian cells have been implicated in vesicle movement.