Format

Send to

Choose Destination
See comment in PubMed Commons below
Mol Biol Cell. 2009 Mar;20(6):1705-14. doi: 10.1091/mbc.E08-03-0282. Epub 2009 Jan 21.

The SM protein Car/Vps33A regulates SNARE-mediated trafficking to lysosomes and lysosome-related organelles.

Author information

1
Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390-9111, USA.

Abstract

The SM proteins Vps33A and Vps33B are believed to act in membrane fusions in endosomal pathways, but their specific roles are controversial. In Drosophila, Vps33A is the product of the carnation (car) gene. We generated a null allele of car to test its requirement for trafficking to different organelles. Complete loss of car function is lethal during larval development. Eye-specific loss of Car causes late, light-independent degeneration of photoreceptor cells. Earlier in these cells, two distinct phenotypes were detected. In young adults, autophagosomes amassed indicating that their fusion with lysosomes requires Car. In eye discs, endocytosed receptors and ligands accumulate in Rab7-positive prelysosomal compartments. The requirement of Car for late endosome-to-lysosome fusion in imaginal discs is specific as early endosomes are unaffected. Furthermore, lysosomal delivery is not restored by expression of dVps33B. This specificity reflects the distinct pattern of binding to different Syntaxins in vitro: dVps33B predominantly binds the early endosomal Avl and Car to dSyntaxin16. Consistent with a role in Car-mediated fusion, dSyntaxin16 is not restricted to Golgi membranes but also present on lysosomes.

PMID:
19158398
PMCID:
PMC2655250
DOI:
10.1091/mbc.E08-03-0282
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center