|
||
© The Rockefeller University Press,
0021-9525/2001//503 $5.00
The Journal of Cell Biology, Volume 152, Number 3,
, 2001 503-518
Original Article |
Erv41p and Erv46p
: New Components of Copii Vesicles Involved in Transport between the ER and Golgi Complex
b Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense University, DK-5230 Odense M, Denmark
Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755.(603) 650-1353(603) 650-6516
charles.barlowe{at}dartmouth.edu
Proteins contained on purified COPII vesicles were analyzed by matrix-assisted laser desorption ionization mass spectrometry combined with database searching. We identified four known vesicle proteins (Erv14p, Bet1p, Emp24p, and Erv25p) and an additional nine species (Yip3p, Rer1p, Erp1p, Erp2p, Erv29p, Yif1p, Erv41p, Erv46p, and Emp47p) that had not been localized to ER vesicles. Using antibodies, we demonstrate that these proteins are selectively and efficiently packaged into COPII vesicles. Three of the newly identified vesicle proteins (Erv29p, Erv41p, and Erv46p) represent uncharacterized integral membrane proteins that are conserved across species. Erv41p and Erv46p were further characterized. These proteins colocalized to ER and Golgi membranes and exist in a detergent-soluble complex that was isolated by immunoprecipitation. Yeast strains lacking Erv41p and/or Erv46p are viable but display cold sensitivity. The expression levels of Erv41p and Erv46p are interdependent such that Erv46p was reduced in an erv41
strain, and Erv41p was not detected in an erv46
strain. When the erv41
or ev46
alleles were combined with other mutations in the early secretory pathway, altered growth phenotypes were observed in some of the double mutant strains. A cell-free assay that reproduces transport between the ER and Golgi indicates that deletion of the Erv41p–Erv46p complex influences the membrane fusion stage of transport.
Key Words: ER Golgi vesicles coat proteins trafficking
© 2001 The Rockefeller University Press
Abbreviations used in this paper: CPY, carboxypeptidase Y; Erv, ER vesicle; gp-
-F, glyco-pro–
factor; HA, hemagglutinin.
|
|