RRC ID 6676
Author Bogdanovic A, Bennett N, Kieffer S, Louwagie M, Morio T, Garin J, Satre M, Bruckert F.
Title Syntaxin 7, syntaxin 8, Vti1 and VAMP7 (vesicle-associated membrane protein 7) form an active SNARE complex for early macropinocytic compartment fusion in Dictyostelium discoideum.
Journal Biochem. J.
Abstract The macropinocytic pathway in Dictyostelium discoideum is organized linearly. After actin-driven internalization, fluid material passes sequentially from endosomes to lysosomes, where molecules are degraded and absorbed. Residual material is exocytosed via post-lysosomal compartments. Syntaxin 7 is a SNARE (soluble N -ethylmaleimide-sensitive fusion protein attachment protein receptor) protein that is present and active in D. discoideum endosomes [Bogdanovic, Bruckert, Morio and Satre (2000) J. Biol. Chem. 275, 36691-36697]. Here we report the identification of its main SNARE partners by co-immunoprecipitation and MS peptide sequencing. The syntaxin 7 complex contains two co-t-SNAREs [Vti1 (Vps10p tail interactor 1) and syntaxin 8] and a v-SNARE [VAMP7 (vesicle-associated membrane protein 7)] (where t-SNAREs are SNAREs of the target compartment and v-SNAREs are SNAREs present in donor vesicles). In endosomes and in vitro, syntaxin 7, Vti1 and syntaxin 8 form a complex that is able to bind VAMP7. Antibodies to syntaxin 8 and a soluble recombinant VAMP7 fragment both inhibit in vitro reconstituted D. discoideum endosome fusion. The lysosomal content of syntaxin 7, Vti1, syntaxin 8 and VAMP7 is low compared with that in endosomes, implying a highly active recycling or retention mechanism. A likely model is that VAMP7 is a v-SNARE present on vesicles carrying lysosomal enzymes, and that the syntaxin 7-Vti1-syntaxin 8 t-SNARE complex is associated with incoming endocytic material.
Volume 368(Pt 1)
Pages 29-39
Published 2002-11-15
DOI 10.1042/BJ20020845
PII BJ20020845
PMID 12175335
PMC PMC1222979
MeSH Amino Acid Sequence Animals Carrier Proteins / metabolism* Dictyostelium / metabolism* Endosomes / metabolism Humans Membrane Fusion Membrane Proteins / metabolism* Molecular Sequence Data Pinocytosis Protozoan Proteins / metabolism* Qa-SNARE Proteins Qb-SNARE Proteins R-SNARE Proteins SNARE Proteins Vesicular Transport Proteins*
IF 4.331
Times Cited 30
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