2c5i
From Proteopedia
N-TERMINAL DOMAIN OF TLG1 COMPLEXED WITH N-TERMINUS OF VPS51 IN DISTORTED CONFORMATION
Structural highlights
Function[VPS51_YEAST] Involved in retrograde transport from early and late endosomes to late Golgi. Links the Golgi-associated retrograde protein (GARP) complex to the t-SNARE TLG1, leading to the fusion between the endosomal vesicles with the late Golgi. May also be indirectly involved in apical bud growth.[1] [2] [3] [4] [5] [TLG1_YEAST] SNARE protein (of Qc type) involved in membrane fusion probably in retrograde traffic of cytosolic double-membrane vesicles derived from both, early and possibly late endosomes/PVC (prevacuolar compartment) back to the trans-Golgi network (TGN or late Golgi). It has been reported to function both as a (target membrane) t-SNARE and as a (vesicle) v-SNARE. Upon vesicle tethering to the target membrane, which requires additional proteins, a SNARE-pin is formed. This is a very stable 4 parallel alpha-helical coil bundle consisting of 4 SNARE domains (usually one of each type: Qa, Qb, Qc, and R), of which at least one is anchored in the opposite membrane. The formation of the SNARE-pin is believed to bring the two membranes in close proximity and to provide the energy to drive membrane fusion. Through its interaction with the VFT (or GARP) complex, it may also contribute to vesicle recognition specificity and tethering. Regulation of SNARE-pin formation also seems to depend on the phosphorylation state of the protein, phosphorylation by TPK1 causing inhibition and dephosphorylation by SIT4 activation.[6] [7] [8] [9] [10] [11] Publication Abstract from PubMedMembrane fusion in cells involves the interaction of SNARE proteins on apposing membranes. Formation of SNARE complexes is preceded by tethering events, and a number of protein complexes that are thought to mediate this have been identified. The VFT or GARP complex is required for endosome-Golgi traffic in yeast. It consists of four subunits, one of which, Vps51, has been shown to bind specifically to the SNARE Tlg1, which participates in the same fusion event. We have determined the structure of the N-terminal domain of Tlg1 bound to a peptide from the N terminus of Vps51. Binding depends mainly on residues 18-30 of Vps51. These form a short helix which lies in a conserved groove in the three-helix bundle formed by Tlg1. Surprisingly, although both Vps51 and Tlg1 are required for transport to the late Golgi from endosomes, removal of the Tlg1-binding sequences from Vps51 does not block such traffic in vivo. Thus, this particular interaction cannot be crucial to the process of vesicle docking or fusion. Structural analysis of the interaction between the SNARE Tlg1 and Vps51.,Fridmann-Sirkis Y, Kent HM, Lewis MJ, Evans PR, Pelham HR Traffic. 2006 Feb;7(2):182-90. PMID:16420526[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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