Structure of palmitoylated BET3: insights into TRAPP complex assembly and membrane localization

Item Type:	Article
Title:	Structure of palmitoylated BET3: insights into TRAPP complex assembly and membrane localization
Creators Name:	Turnbull, A.P. and Kuemmel, D. and Prinz, B. and Holz, C. and Schultchen, J. and Lang, C. and Niesen, F.H. and Hofmann, K.P. and Delbrueck, H. and Behlke, J. and Mueller, E.C. and Jarosch, E. and Sommer, T. and Heinemann, U.
Abstract:	BET3 is a component of TRAPP, a complex involved in the tethering of transport vesicles to the cis-Golgi membrane. The crystal structure of human BET3 has been determined to 1.55-Å resolution. BET3 adopts an α/β-plait fold and forms dimers in the crystal and in solution, which pre-determines the architecture of TRAPP where subunits are present in equimolar stoichiometry. A hydrophobic pocket within BET3 buries a palmitate bound through a thioester linkage to cysteine 68. BET3 and yeast Bet3p are palmitoylated in recombinant yeast cells, the mutant proteins BET3 C68S and Bet3p C80S remain unmodified. Both BET3 and BET3 C68S are found in membrane and cytosolic fractions of these cells; in membrane extractions, they behave like tightly membrane-associated proteins. In a deletion strain, both Bet3p and Bet3p C80S rescue cell viability. Thus, palmitoylation is neither required for viability nor sufficient for membrane association of BET3, which may depend on protein-protein contacts within TRAPP or additional, yet unidentified modifications of BETS. A conformational change may facilitate palmitoyl extrusion from BET3 and allow the fatty acid chain to engage in intermolecular hydrophobic interactions.
Keywords:	α/β-Plait, BET3 Protein, Protein Palmitoylation, TRAPP Complex, Vesicle Tethering
Source:	EMBO Journal
ISSN:	0261-4189
Publisher:	Nature Publishing Group
Volume:	24
Number:	5
Page Range:	875-884
Date:	1 January 2005
PubMed:	View item in PubMed

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