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The structural basis for activation of the Rab Ypt1p by the TRAPP membrane-tethering complexes.
- Source :
-
Cell [Cell] 2008 Jun 27; Vol. 133 (7), pp. 1202-13. - Publication Year :
- 2008
-
Abstract
- The multimeric membrane-tethering complexes TRAPPI and TRAPPII share seven subunits, of which four (Bet3p, Bet5p, Trs23p, and Trs31p) are minimally needed to activate the Rab GTPase Ypt1p in an event preceding membrane fusion. Here, we present the structure of a heteropentameric TRAPPI assembly complexed with Ypt1p. We propose that TRAPPI facilitates nucleotide exchange primarily by stabilizing the nucleotide-binding pocket of Ypt1p in an open, solvent-accessible form. Bet3p, Bet5p, and Trs23p interact directly with Ypt1p to stabilize this form, while the C terminus of Bet3p invades the pocket to participate in its remodeling. The Trs31p subunit does not interact directly with the GTPase but allosterically regulates the TRAPPI interface with Ypt1p. Our findings imply that TRAPPII activates Ypt1p by an identical mechanism. This view of a multimeric membrane-tethering assembly complexed with a Rab provides a framework for understanding events preceding membrane fusion at the molecular level.
- Subjects :
- Endoplasmic Reticulum metabolism
Enzyme Activation
Golgi Apparatus metabolism
Guanine Nucleotide Exchange Factors chemistry
Guanine Nucleotide Exchange Factors metabolism
Models, Molecular
Protein Interaction Mapping
Saccharomyces cerevisiae cytology
Saccharomyces cerevisiae enzymology
Saccharomyces cerevisiae Proteins chemistry
Saccharomyces cerevisiae Proteins genetics
Vesicular Transport Proteins chemistry
Vesicular Transport Proteins genetics
rab GTP-Binding Proteins chemistry
Saccharomyces cerevisiae metabolism
Saccharomyces cerevisiae Proteins metabolism
Vesicular Transport Proteins metabolism
rab GTP-Binding Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1097-4172
- Volume :
- 133
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- Cell
- Publication Type :
- Academic Journal
- Accession number :
- 18585354
- Full Text :
- https://doi.org/10.1016/j.cell.2008.04.049