BET3 encodes a novel hydrophilic protein that acts in conjunction with yeast SNAREs.
Here we report the identification of BET3, a new member of a group of interacting genes whose products have been implicated in the targeting and fusion of endoplasmic reticulum (ER) to Golgi transport vesicles with their acceptor compartment. A temperature-sensitive mutant in bet3-1 was isolated in a synthetic lethal screen designed to identify new genes whose products may interact with BET1, a type II integral membrane protein that is required for ER to Golgi transport. At 37 degrees C, bet3-1 fails to transport invertase, alpha-factor, and carboxypeptidase Y from the ER to the Golgi complex. As a consequence, this mutant accumulates dilated ER and small vesicles. The SNARE complex, a docking/fusion complex, fails to form in this mutant. Furthermore, BET3 encodes an essential 22-kDa hydrophilic protein that is conserved in evolution, which is not a component of this complex. These findings support the hypothesis that Bet3p may act before the assembly of the SNARE complex.
Rossi
G
G
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Kolstad
K
K
Stone
S
S
Palluault
F
F
Ferro-Novick
S
S
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D005656:Fungal Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D005800:Genes, Fungal; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins
C098389:BET3 protein, S cerevisiae; D005656:Fungal Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins