Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Mol Biol Cell. 1999 Nov;10(11):3549-65.

Shr3p mediates specific COPII coatomer-cargo interactions required for the packaging of amino acid permeases into ER-derived transport vesicles.

Author information

  • 1Ludwig Institute for Cancer Research, S-171 77 Stockholm, Sweden.

Abstract

The SHR3 gene of Saccharomyces cerevisiae encodes an integral membrane component of the endoplasmic reticulum (ER) with four membrane-spanning segments and a hydrophilic, cytoplasmically oriented carboxyl-terminal domain. Mutations in SHR3 specifically impede the transport of all 18 members of the amino acid permease (aap) gene family away from the ER. Shr3p does not itself exit the ER. Aaps fully integrate into the ER membrane and fold properly independently of Shr3p. Shr3p physically associates with the general aap Gap1p but not Sec61p, Gal2p, or Pma1p in a complex that can be purified from N-dodecylmaltoside-solubilized membranes. Pulse-chase experiments indicate that the Shr3p-Gap1p association is transient, a reflection of the exit of Gap1p from the ER. The ER-derived vesicle COPII coatomer components Sec13p, Sec23p, Sec24p, and Sec31p but not Sar1p bind Shr3p via interactions with its carboxyl-terminal domain. The mutant shr3-23p, a nonfunctional membrane-associated protein, is unable to associate with aaps but retains the capacity to bind COPII components. The overexpression of either Shr3p or shr3-23p partially suppresses the temperature-sensitive sec12-1 allele. These results are consistent with a model in which Shr3p acts as a packaging chaperone that initiates ER-derived transport vesicle formation in the proximity of aaps by facilitating the membrane association and assembly of COPII coatomer components.

PMID:
10564255
[PubMed - indexed for MEDLINE]
PMCID:
PMC25634
Free PMC Article

Images from this publication.See all images (10)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk