The Emp24 complex recruits a specific cargo molecule into endoplasmic reticulum-derived vesicles

Members of the yeast p24 family, including Emp24p and Erv25p, form a hetero meric complex required for the efficient transport of selected proteins fro m the endoplasmic reticulum (ER) to the Golgi apparatus. The specific funct ions and sites of action of this complex are unknown. We show that Emp24p i s directly required for efficient packaging of a lumenal cargo protein, Gas 1p, into ER-derived vesicles. Emp24p and Erv25p can be directly cross-linke d to Gas1p in ER-derived vesicles, Gap1p, which was not affected by emp24 m utation, was not cross-linked. These results suggest that the Emp24 complex acts as a cargo receptor in vesicle biogenesis from the ER.