Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
EMBO J. 2009 Nov 4;28(21):3279-89. doi: 10.1038/emboj.2009.269. Epub 2009 Sep 17.

Visualization of cargo concentration by COPII minimal machinery in a planar lipid membrane.

Author information

  • 1Department of Biomolecular Energetics, The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.

Abstract

Selective protein export from the endoplasmic reticulum is mediated by COPII vesicles. Here, we investigated the dynamics of fluorescently labelled cargo and non-cargo proteins during COPII vesicle formation using single-molecule microscopy combined with an artificial planar lipid bilayer. Single-molecule analysis showed that the Sar1p-Sec23/24p-cargo complex, but not the Sar1p-Sec23/24p complex, undergoes partial dimerization before Sec13/31p recruitment. On addition of a complete COPII mixture, cargo molecules start to assemble into fluorescent spots and clusters followed by vesicle release from the planar membrane. We show that continuous GTPase cycles of Sar1p facilitate cargo concentration into COPII vesicle buds, and at the same time, non-cargo proteins are excluded from cargo clusters. We propose that the minimal set of COPII components is required not only to concentrate cargo molecules, but also to mediate exclusion of non-cargo proteins from the COPII vesicles.

PMID:
19763084
[PubMed - indexed for MEDLINE]
PMCID:
PMC2776102
Free PMC Article

Images from this publication.See all images (4)Free text

Figure 1
Figure 2
Figure 3
Figure 4
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