Myosin-I in mammalian liver.
Myosin-I in mammalian liver.
复制标题
哺乳动物肝脏中的肌球蛋白-I。
DOI：
10.1002/cm.970240306
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发表时间：
1993
影响因子：
--
通讯作者：
Conaty,C
中科院分区：
文献类型：
--
作者：
Coluccio,LM;Conaty,C
肌球蛋白I是一类分子量约为110 kDa的蛋白，具有常规肌球蛋白的特性，但不能形成细丝。先前的研究表明肌球蛋白- 1参与了包括细胞迁移和吞噬在内的细胞运动过程。虽然myosin - I在高等真核生物中的第一个例子是肠110K -钙调蛋白复合物，它在微绒毛中形成连接肌动蛋白丝核心束和膜的侧链，但myosin - I现在已被证明是大鼠肾脏的一个组成部分，并且存在于牛肾上腺和大脑中。我们现在已经从大鼠肝脏中纯化并鉴定了两种多肽，它们具有肠110K‐钙调蛋白复合物的几个特征。两种肝脏多肽都用ATP和钙调素凝胶过滤的共洗脱液溶解。110 - kDa和130 - kDa的多肽在1mm EGTA中结合钙调素。这两种多肽都以ATP可逆的方式与F -肌动蛋白结合，并交联肌动蛋白丝。纯化的多肽具有肌动蛋白激活的Mg2+ - atp酶活性，具有典型的刷状边界肌球蛋白- 1活性。一种针对鸡肠110 - kDa多肽的多克隆抗血清能识别这两种大鼠肝脏多肽，而另一种血清能识别130 - kDa而不能识别110 - kDa大鼠肝脏多肽。α -胰凝乳酶对纯化多肽的控制蛋白水解表明这两种多肽是不同的，但又相关。分离肝细胞的免疫荧光显微镜显示肌球蛋白I呈囊泡状分布，分布在整个细胞质中，但更集中在细胞核附近。这些数据通过几个功能标准提供了新的证据，表明多个肌球蛋白- 1分子存在于高等生物中，并可能共存于单一细胞类型中。©1993 Wiley‐Liss, Inc。
Myosin‐I refers to a class of proteins with a molecular weight of approximately 110‐kDa, which have characteristics of conventional myosin but are unable to form filaments. Previous studies have implicated myosin‐I in motile cellular processes including cell migration and phagocytosis. Although the first example of myosin‐I in higher eukaryotes was the intestinal 110K‐calmodulin complex, which forms in microvilli the lateral links connecting the core bundle of actin filaments to the membrane, myosin‐I has now been shown to be a component of rat kidney and to be present in bovine adrenal gland and brain. We have now purified and characterized two polypeptides from rat liver which have several characteristics of the intestinal 110K‐calmodulin complex. Both liver polypeptides are solubilized with ATP and co‐elute on gel filtration with calmodulin. The polypeptides, of 110‐kDa and 130‐kDa, bind calmodulin in 1 mM EGTA. Both polypeptides bind to F‐actin in an ATP reversible fashion, and crosslink actin filaments. The purified polypeptides possess an actin‐activated Mg2+‐ATPase activity typical of brush border myosin‐I. A polyclonal antiserum directed against the chicken intestinal 110‐kDa polypeptide recognizes both rat liver polypeptides, whereas another serum recognizes the 130‐kDa but not the 110‐kDa rat liver polypeptide. Controlled proteolysis of the purified polypeptides with α‐chymotrypsin indicates that the two polypeptides are distinct but related. Immunofluorescence microscopy on isolated hepatocytes shows distribution of myosin‐I to be vesicular, distributed throughout the cytoplasm, but more concentrated near the nucleus. These data contribute new evidence by several functional criteria that multiple myosin‐I molecules are present in higher organisms and may coexist in a single cell type. © 1993 Wiley‐Liss, Inc.