Binding of brush border myosin I to phospholipid vesicles.
Binding of brush border myosin I to phospholipid vesicles.
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DOI：
10.1083/jcb.111.2.443
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发表时间：
1990-08
期刊：
影响因子：
--
通讯作者：
Mooseker MS
中科院分区：
文献类型：
--
作者：
Hayden SM;Wolenski JS;Mooseker MS
肠上皮细胞微绒毛内的肌动蛋白丝芯通过刷状边界肌动蛋白I（一种肌动蛋白-钙调蛋白复合物，属于肌动蛋白类机械酶）向外附着在质膜上。在本报告中，研究了BB肌球蛋白I与纯磷脂囊泡的结合并对其进行了表征。BB肌球蛋白I可与阴离子磷脂组成的脂质体饱和结合，但不与仅由中性磷脂组成的脂质体结合。BB肌球蛋白I与磷脂酰丝氨酸和磷脂酰甘油囊泡的结合在4-5 × 10(-3) nmol蛋白/nmol磷脂的条件下达到饱和，而表观解离常数被确定为1-3 × 10(-7) m。与游离蛋白类似，膜相关BB肌球蛋白I以atp敏感的方式结合f -肌动蛋白，并表现出肌动蛋白激活的mg - atp酶活性。免疫印迹分析由囊泡结合的BB肌球蛋白I控制蛋白水解产生的肽提供了有关膜相互作用部位的结构信息。用结构域特异性单克隆抗体进行免疫印迹染色，发现一系列羧基末端脂粒相关肽被保护，不被消化，这表明膜结合结构域位于BB肌球蛋白I重链的羧基末端“尾部”。
The actin filament core within each microvillus of the intestinal epithelial cell is attached laterally to the plasma membrane by brush border (BB) myosin I, a protein-calmodulin complex belonging to the myosin I class of actin-based mechanoenzymes. In this report, the binding of BB myosin I to pure phospholipid vesicles was examined and characterized. BB myosin I demonstrated saturable binding to liposomes composed of anionic phospholipids, but did not associate with liposomes composed of only neutral phospholipids. The binding of BB myosin I to phosphatidylserine and phosphatidylglycerol vesicles reached saturation at 4-5 x 10(-3) nmol protein/nmol phospholipid, while the apparent dissociation constant was determined to be 1-3 x 10(-7) M. Similar to the free protein, membrane-associated BB myosin I bound F-actin in an ATP-sensitive manner and demonstrated actin-activated Mg-ATPase activity. Immunoblot analysis of peptides generated from controlled proteolysis of vesicle-bound BB myosin I provided structural information concerning the site responsible for the membrane interaction. Immunoblot staining with domain-specific mAbs revealed a series of COOH-terminal, liposome-associated peptides that were protected from digestion, suggesting that the membrane-binding domain is within the carboxy-terminal "tail" of the BB myosin I heavy chain.