The Emp24 Complex Recruits a Specific Cargo Molecule into Endoplasmic Reticulum–Derived Vesicles

TLDR

Yeast p24 proteins Emp24p and Erv25p form a heteromeric complex essential for transporting selected proteins from the ER to the Golgi, though its precise function and site remain unclear. Emp24p is essential for packaging the lumenal cargo Gas1p into ER‑derived vesicles, as demonstrated by direct cross‑linking of Emp24p and Erv25p to Gas1p but not to Gap1p, indicating that the Emp24 complex acts as a cargo receptor in ER vesicle biogenesis.

Abstract

Members of the yeast p24 family, including Emp24p and Erv25p, form a heteromeric complex required for the efficient transport of selected proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. The specific functions and sites of action of this complex are unknown. We show that Emp24p is directly required for efficient packaging of a lumenal cargo protein, Gas1p, into ER-derived vesicles. Emp24p and Erv25p can be directly cross-linked to Gas1p in ER-derived vesicles. Gap1p, which was not affected by emp24 mutation, was not cross-linked. These results suggest that the Emp24 complex acts as a cargo receptor in vesicle biogenesis from the ER.