7u6f
From Proteopedia
Mouse retromer (VPS26/VPS35/VPS29) heterotrimers
Structural highlights
FunctionVPS35_MOUSE Acts as component of the retromer cargo-selective complex (CSC). The CSC is believed to be the core functional component of retromer or respective retromer complex variants acting to prevent missorting of selected transmembrane cargo proteins into the lysosomal degradation pathway. The recruitment of the CSC to the endosomal membrane involves RAB7A and SNX3. The CSC seems to associate with the cytoplasmic domain of cargo proteins predominantly via VPS35; however, these interactions seem to be of low affinity and retromer SNX proteins may also contribute to cargo selectivity thus questioning the classical function of the CSC. The SNX-BAR retromer mediates retrograde transport of cargo proteins from endosomes to the trans-Golgi network (TGN) and is involved in endosome-to-plasma membrane transport for cargo protein recycling. The SNX3-retromer mediates the retrograde transport of WLS distinct from the SNX-BAR retromer pathway. The SNX27-retromer is believed to be involved in endosome-to-plasma membrane trafficking and recycling of a broad spectrum of cargo proteins. The CSC seems to act as recruitment hub for other proteins, such as the WASH complex and TBC1D5 (Probable). Required for retrograde transport of lysosomal enzyme receptor IGF2R and SLC11A2. Required to regulate transcytosis of the polymeric immunoglobulin receptor (pIgR-pIgA). Required for endosomal localization of WASHC2 and mediates the association of the CSC with the WASH complex (By similarity).[UniProtKB:Q96QK1] Publication Abstract from PubMedRetromer (VPS26/VPS35/VPS29 subunits) assembles with multiple sorting nexin proteins on membranes to mediate endosomal recycling of transmembrane protein cargoes. Retromer has been implicated in other cellular processes, including mitochondrial homeostasis, nutrient sensing, autophagy, and fission events. Mechanisms for mammalian retromer assembly remain undefined, and retromer engages multiple sorting nexin proteins to sort cargoes to different destinations. Published structures demonstrate mammalian retromer forms oligomers in vitro, but several structures were poorly resolved. We report here improved retromer oligomer structures using single-particle cryo-EM by combining data collected from tilted specimens with multiple advancements in data processing, including using a 3D starting model for enhanced automated particle picking in RELION. We used a retromer mutant (3KE retromer) that breaks VPS35-mediated interfaces to determine a structure of a new assembly interface formed by the VPS26A and VPS35 N-termini. The interface reveals how an N-terminal VPS26A arrestin saddle can link retromer chains by engaging a neighboring VPS35 N- terminus, on the opposite side from the well-characterized C-VPS26/N-VPS35 interaction observed within heterotrimers. The new interaction interface exhibits substantial buried surface area ( approximately 7000 A(2)) and further suggests that metazoan retromer may serve as an adaptable scaffold. Improved mammalian retromer cryo-EM structures reveal a new assembly interface.,Kendall AK, Chandra M, Xie B, Wan W, Jackson LP J Biol Chem. 2022 Sep 26;298(11):102523. doi: 10.1016/j.jbc.2022.102523. PMID:36174678[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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