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

Mohammed A. Akbar, Sanchali Ray, Helmut Krämer

Research output: Contribution to journalArticle

56 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)1705-1714
Number of pages10
JournalMolecular Biology of the Cell
Volume20
Issue number6
DOIs
StatePublished - Mar 15 2009

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Dianthus
SNARE Proteins
Lysosomes
Organelles
Endosomes
Qa-SNARE Proteins
Imaginal Discs
Photoreceptor Cells
Proteins
Membrane Fusion
Endocytosis
Drosophila
Young Adult
Alleles
Ligands
Phenotype
Light
Membranes
Genes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

The SM protein car/Vps33A regulates SNARE-mediated trafficking to lysosomes and lysosome-related organelles. / Akbar, Mohammed A.; Ray, Sanchali; Krämer, Helmut.

In: Molecular Biology of the Cell, Vol. 20, No. 6, 15.03.2009, p. 1705-1714.

Research output: Contribution to journalArticle

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