COPII

COPII vesicles are transport intermediates from the endoplasmic reticulum. The process is driven by recruitment of the soluble proteins that form the coat structure called COPII from the cytoplasm to the membrane. 

Biosynthetic and secretory cargo leaving the ER is packaged in COPII-coated vesicles for delivery to the Golgi complex 146 The Golgi apparatus is a highly polarized structure consisting of a series of flattened cisternae, usually located near the nucleus and the centrosome 146... 

Barlowe, C. COPII-dependent transport from the endoplasmic reticulum. Curr. Opin. Cell Biol. 14 417-422, 2002. 

Jones B, Jones EL, Bonney SA, Patel HN, Mensenkamp AR, Eichenbaum-Voline S, Rudling M, Myrdal U, Annesi G, Naik S, Meadows N, Quattrone A, Islam SA, Naoumova RP, Angelin B, Infante R, Levy E, Roy CC, Freemont PS, Scott J, Shoulders CC (2003) Mutations in a Sari GTPase of COPII vesicles are associated with lipid absorption disorders. Nat Genet 34 29-31... 

Proteins associated with the PDZ ligand of the 5-HT4e receptor C-terminus are completely different from those that bind to the 5-HT4a receptors. They include the neuronal isoform of nitric oxide synthase (nNOS) and CIPP, two PDZ-domain-containing proteins, and Sec 23, which lacks any obvious PDZ domain (9). Sec 23 is a member of a protein complex designated as COPII, which is involved in the budding of vesicles from the endoplasmic reticulum (ER) and ER-to-Golgi transport of proteins. 

Icosahedral capsid viruses and clathrins are examples of coat proteins of which there are many. Another example that has been extensively studied is coat protein II, or COPII, which is composed of an inner cage and outer coat [5], The inner cage is a cuboctahedron approximately 60 nm across. It has square and triangular faces which can only be constructed if four protein strands emanate from the structure s hub, rather than the three seen in clathrins. It also transpires that the proteins interact with each other at the vertices without any of the extensive interdigitation seen in clathrin cages. 

In contrast to the COPII cage, the outer coat is an icosidodecahedron composed of pentagons and triangles. With a diameter of 100 nm it is able to encapsulate the cage and its contents. COPII carries materials downstream from the endoplasmic reticulum to cell surfaces and other routes of excretion. 

Stagg SM et al (2008) Structural basis for cargo regulation of COPII coat assembly. Cell 134 474 184... 

Wang X, Matteson J, An Y, Moyer B, Yoo JS, Bannykh S, Wilson lA, Riordan JR, Batch WE. COPII-dependent export of cystic fibrosis transmembrane conductance regulator from the ER uses a di-acidic exit code. J. Cell Biol. 2004 167 65-74. 

Kappeler F, Klopfenstein DR, Foguet M, Paccaud IP, Hauri HP. The recycling of ERGIC-53 in the early secretory pathway. ERGIC-53 carries a cytosolic endoplasmic reticulum-exit determinant interacting with COPII. J. Biol. Chem. 1997 272 31801-31808. 

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