3cue
Crystal structure of a TRAPP subassembly activating the Rab Ypt1p
Structural highlights
FunctionTRS23_YEAST Component of the TRAPP I, TRAPP II and TRAPP III complexes which act as guanine nucleotide exchange factors (GEF) for YPT1. TRAPP I plays a key role in the late stages of endoplasmic reticulum to Golgi traffic. TRAPP II plays a role in intra-Golgi transport. TRAPP III plays a role in autophagosome formation.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. The structural basis for activation of the Rab Ypt1p by the TRAPP membrane-tethering complexes.,Cai Y, Chin HF, Lazarova D, Menon S, Fu C, Cai H, Sclafani A, Rodgers DW, De La Cruz EM, Ferro-Novick S, Reinisch KM Cell. 2008 Jun 27;133(7):1202-13. PMID:18585354[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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