Ceramide biosynthesis is required for the formation of the oligomeric H⁺-ATPase Pma1p in the yeast endoplasmic reticulum

TY - JOUR

T1 - Ceramide biosynthesis is required for the formation of the oligomeric H+-ATPase Pma1p in the yeast endoplasmic reticulum

AU - Lee, Marcus C.S.

AU - Hamamoto, Susan

AU - Schekman, Randy

PY - 2002/6

Y1 - 2002/6

N2 - The yeast plasma membrane H+-ATPase Pma1p is one of the most abundant proteins to traverse the secretory pathway. Newly synthesized Pma1p exits the endoplasmic reticulum (ER) via COPII-coated vesicles bound for the Golgi. Unlike most secreted proteins, efficient incorporation of Pma1p into COPII vesicles requires the Sec24p homolog Lst1p, suggesting a unique role for Lst1p in ER export. Vesicles formed with mixed Sec24p-Lst1p coats are larger than those with Sec24p alone. Here, we examined the relationship between Pma1p bio-synthesis and the requirement for this novel coat subunit. We show that Pma1p forms a large oligomeric complex of > 1 MDa in the ER, which is packaged into COPII vesicles. Furthermore, oligomerization of Pma1p is linked to membrane lipid composition; Pma1p is rendered monomeric in cells depleted of ceramide, suggesting that association with lipid rafts may influence oligomerization. Surprisingly, monomeric Pma1p present in ceramide-deficient membranes can be exported from the ER in COPII vesicles in a reaction that is stimulated by Lst1p. We suggest that Lst1p directly conveys Pma1p into a COPII vesicle and that the larger size of mixed Sec24pLst1p COPII vesicles is not essential to the packaging of large oligomeric complexes.

AB - The yeast plasma membrane H+-ATPase Pma1p is one of the most abundant proteins to traverse the secretory pathway. Newly synthesized Pma1p exits the endoplasmic reticulum (ER) via COPII-coated vesicles bound for the Golgi. Unlike most secreted proteins, efficient incorporation of Pma1p into COPII vesicles requires the Sec24p homolog Lst1p, suggesting a unique role for Lst1p in ER export. Vesicles formed with mixed Sec24p-Lst1p coats are larger than those with Sec24p alone. Here, we examined the relationship between Pma1p bio-synthesis and the requirement for this novel coat subunit. We show that Pma1p forms a large oligomeric complex of > 1 MDa in the ER, which is packaged into COPII vesicles. Furthermore, oligomerization of Pma1p is linked to membrane lipid composition; Pma1p is rendered monomeric in cells depleted of ceramide, suggesting that association with lipid rafts may influence oligomerization. Surprisingly, monomeric Pma1p present in ceramide-deficient membranes can be exported from the ER in COPII vesicles in a reaction that is stimulated by Lst1p. We suggest that Lst1p directly conveys Pma1p into a COPII vesicle and that the larger size of mixed Sec24pLst1p COPII vesicles is not essential to the packaging of large oligomeric complexes.

UR - https://www.scopus.com/pages/publications/0037151098

U2 - 10.1074/jbc.M200450200

DO - 10.1074/jbc.M200450200

M3 - Article

C2 - 11950838

AN - SCOPUS:0037151098

SN - 0021-9258

VL - 277

SP - 22395

EP - 22401

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 25

ER -