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  • VARP Is Recruited on to End...
    Hesketh, Geoffrey G.; Pérez-Dorado, Inmaculada; Jackson, Lauren P.; Wartosch, Lena; Schäfer, Ingmar B.; Gray, Sally R.; McCoy, Airlie J.; Zeldin, Oliver B.; Garman, Elspeth F.; Harbour, Michael E.; Evans, Philip R.; Seaman, Matthew N.J.; Luzio, J. Paul; Owen, David J.

    Developmental cell, 06/2014, Letnik: 29, Številka: 5
    Journal Article

    VARP is a Rab32/38 effector that also binds to the endosomal/lysosomal R-SNARE VAMP7. VARP binding regulates VAMP7 participation in SNARE complex formation and can therefore influence VAMP7-mediated membrane fusion events. Mutant versions of VARP that cannot bind Rab32:GTP, designed on the basis of the VARP ankyrin repeat/Rab32:GTP complex structure described here, unexpectedly retain endosomal localization, showing that VARP recruitment is not dependent on Rab32 binding. We show that recruitment of VARP to the endosomal membrane is mediated by its direct interaction with VPS29, a subunit of the retromer complex, which is involved in trafficking from endosomes to the TGN and the cell surface. Transport of GLUT1 from endosomes to the cell surface requires VARP, VPS29, and VAMP7 and depends on the direct interaction between VPS29 and VARP. Finally, we propose that endocytic cycling of VAMP7 depends on its interaction with VARP and, consequently, also on retromer. •VARP recruitment to endosomes does not depend on its interaction with Rab32:GTP•VARP contains two Zinc-binding CHPLCxCxxC motifs that bind the retromer subunit VPS29•VARP is recruited to endosomes through its interaction with VPS29•VARP, retromer, and VAMP7 are all involved in trafficking of GLUT1 to the cell surface The VAMP7-binding Rab32-effector and Rab21GEF VARP binds directly to the retromer subunit VPS29. VARP’s interaction with VPS29 recruits it on to endosomes, thereby linking the cargo sorting retromer complex with an R-SNARE involved in endosomal function. All three are shown to be involved in endosome to cell surface transport.