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Citation
Galindo, A., Planelles-Herrero, V.J., Degliesposti, G., Munro, S. (2021). Cryo-EM structure of metazoan TRAPPIII, the multi-subunit complex that activates the GTPase Rab1.  EMBO J. 40(12): e107608.
FlyBase ID
FBrf0249273
Publication Type
Research paper
Abstract

The TRAPP complexes are nucleotide exchange factors that play essential roles in membrane traffic and autophagy. TRAPPII activates Rab11, and TRAPPIII activates Rab1, with the two complexes sharing a core of small subunits that affect nucleotide exchange but being distinguished by specific large subunits that are essential for activity in vivo. Crystal structures of core subunits have revealed the mechanism of Rab activation, but how the core and the large subunits assemble to form the complexes is unknown. We report a cryo-EM structure of the entire Drosophila TRAPPIII complex. The TRAPPIII-specific subunits TRAPPC8 and TRAPPC11 hold the catalytic core like a pair of tongs, with TRAPPC12 and TRAPPC13 positioned at the joint between them. TRAPPC2 and TRAPPC2L link the core to the two large arms, with the interfaces containing residues affected by disease-causing mutations. The TRAPPC8 arm is positioned such that it would contact Rab1 that is bound to the core, indicating how the arm could determine the specificity of the complex. A lower resolution structure of TRAPPII shows a similar architecture and suggests that the TRAPP complexes evolved from a single ur-TRAPP.

PubMed ID
PubMed Central ID
PMC8204870 (PMC) (EuropePMC)
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Secondary IDs
    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    EMBO J.
    Title
    The EMBO Journal
    Publication Year
    1982-
    ISBN/ISSN
    0261-4189
    Data From Reference