Effects of cytoplasmic acidification on clathrin lattice morphology.
Effects of cytoplasmic acidification on clathrin lattice morphology.
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细胞质酸化对网格蛋白晶格形态的影响。
DOI：
10.1083/jcb.108.2.401
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发表时间：
1989-02
影响因子：
7.8
通讯作者：
Heuser, J
中科院分区：
文献类型：
--
作者：
Heuser, J
通过几种不同的阻止内吞作用的方案降低培养细胞的内部pH，发现可以改变质膜内侧的网状蛋白晶格的结构。晶格向内弯曲，直到它们变成几乎球形，但仍然顽固地附着在膜上。此外，晶格的边缘开出了空荡荡的笼子，笼子周围都是笼子。相应地，在酸化介质中浸泡的破碎细胞在网状蛋白晶格中也表现出类似的变化。酸化加剧了晶格在体外四舍五入的正常趋势，也刺激它们从网状蛋白的纯溶液中成核形成微笼。另一方面，也发现了几种抑制内吞作用的条件，产生了异常平坦的晶格，而不是具有外来微笼的异常弯曲的网状晶格。这些处理包括用黑素在pH中“夹住”细胞，用低渗介质使细胞肿胀，用可溶性多赖氨酸将细胞粘在培养皿表面。同样，在随后的体外酸化过程中，这类细胞中异常平坦的晶格显示出一种圆整和成核的趋势，形成网状蛋白微笼。这表明，无论分子筛晶格的初始曲率如何，它们都表现出在体外生长和增加曲率的能力，并且这一能力随着环境pH的降低而增强。在体内，笼状蛋白晶格的生长和弯曲也可能受到膜受体簇周围的局部pH下降的刺激。
Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.