
Evidence of a role for heterotrimeric GTP-binding proteins in endosome fusion.
Guanosine triphosphate (GTP)-binding proteins are required for intracellular vesicular transport. Mastoparan is a peptide component of wasp venom that increases nucleotide exchange in some classes of G alpha subunits of regulatory heterotrimeric GTP-binding proteins (G proteins). Mastoparan and other compounds that increase nucleotide exchange by G proteins inhibited endosome fusion in vitro and reversed the effects of guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S), a nonhydrolyzable GTP analog. Addition of beta gamma subunits of G proteins to the fusion assay antagonized the stimulatory effect of GTP-gamma-S, confirming the participation of G proteins. These results indicate that GTP-binding proteins are required for endosome fusion and in particular that a G protein is involved. Given the function of G proteins in signal transduction, these findings may provide insight into the mechanism by which endosomal vesicles become competent for fusion after their formation at the cell surface.
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Related Subject Headings
- Wasp Venoms
- Peptides
- Organelles
- Membrane Fusion
- Macromolecular Substances
- Intracellular Membranes
- Intercellular Signaling Peptides and Proteins
- Guanosine Triphosphate
- Guanosine Diphosphate
- Guanosine 5'-O-(3-Thiotriphosphate)
Citation

Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Wasp Venoms
- Peptides
- Organelles
- Membrane Fusion
- Macromolecular Substances
- Intracellular Membranes
- Intercellular Signaling Peptides and Proteins
- Guanosine Triphosphate
- Guanosine Diphosphate
- Guanosine 5'-O-(3-Thiotriphosphate)