Clathrin-coated vesicles from brain have small payloads: A cryo-electron tomographic study

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• 作者：J. Bernard Heymann ; Dennis C. Winkler ; Yang-In Yim ; Evan Eisenberg ; Lois E. Greene ; Alasdair C. Steven
• 关键词：CB ; clathrin basket ; CV ; coated vesicle ; AP ; adaptor protein
• 刊名：Journal of Structural Biology
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：184
• 期：1
• 页码：43-51
• 全文大小：2278 K

文摘

Clathrin coats, which stabilize membrane curvature during endocytosis and vesicular trafficking, form highly polymorphic fullerene lattices. We used cryo-electron tomography to visualize coated particles in isolates from bovine brain. The particles range from ¡«66 to ¡«134 nm in diameter, and only 20 % of them (all ?80 nm) contain vesicles. The remaining 80 % are clathrin ¡°baskets¡±, presumably artifactual assembly products. Polyhedral models were built for 54 distinct coat geometries. In true coated vesicles (CVs), most vesicles are offset to one side, leaving a crescent of interstitial space between the coat and the membrane for adaptor proteins and other components. The latter densities are fewer on the membrane-proximal side, which may represent the last part of the vesicle to bud off. A small number of densities - presumably cargo proteins - are associated with the interior surface of the vesicles. The clathrin coat, adaptor proteins, and vesicle membrane contribute almost all of the mass of a CV, with most cargoes accounting for only a few percent. The assembly of a CV therefore represents a massive biosynthetic effort to internalize a relatively diminutive payload. Such a high investment may be needed to overcome the resistance of membranes to high curvature.