Surface structure of the COPII-coated vesicle
K Matsuoka1, R Schekman, L Orci
1Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3206, USA.
Abstract:
The spatial arrangement of COPII coat protein subunits was analyzed by crosslinking to an artificial membrane surface and by electron microscopy of coat proteins and coated vesicle surfaces. The efficiency of COPII subunit crosslinking to phospholipids declined in order of protein recruitment to the coat: Sar1p > Sec23/24p >> Sec13/31p. Deep-etch rotary shadowing and electron microscopy were used to explore the COPII subunit structure with isolated proteins and coated vesicles. Sec23/24 resembles a bow tie, and Sec13/31p contains terminal bilobed globular structures bordering a central rod. The surface structure of COPII vesicles revealed a coat built with polygonal units. The length of the side of the hexagonal/pentagonal units is close to the dimension of the central rod-like segment of Sec13/31. Partially uncoated profiles revealed strands of Sec13/31p stripped from the vesicle surface. We conclude that the coat subunits form layers displaced from the membrane surface in reverse order of addition to the coat.
Related Concept Videos
Overview of Secretory Vesicles
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
COP Coated Vesicles
Pinching-off of Coated Vesicles
Coat Assembly and GTPases
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Vesicular Tubular Clusters
With the help of motor proteins such...
Clathrin Coated Vesicles


