COPII-coated vesicles carry proteins from the endoplasmic reticulum to the Golgi complex. This vesicular transport can be reconstituted by using three cytosolic components containing five proteins: the small GTPase Sar1p, the Sec23p/24p complex, and the Sec13p/Sec31p complex. This domain is composed of five alpha helices.

1: Structure of the Sec23p/24p and Sec13p/31p complexes of COPII. Lederkremer GZ, Cheng Y, Petre BM, Vogan E, Springer S, Schekman R, Walz T, Kirchhausen T; Proc Natl Acad Sci USA 2001;98:10704-10709. PMID:11535824