The SNX-BAR dimer can associate with endosomes by binding to phosphatidyl inositol 3-phosphate (PtdIns3P) but the retromer cargo-selective complex (CSC) requires Rab7a and Snx3 for recruitment to endosomes (Cozier et al., 2002; Rojas et al., 2008; Seaman et al., 2009; Harterink et al., 2011; Vardarajan et al., 2012; Harrison et al., 2014). In addition to associating with Rab7a and Snx3, the CSC also functions as a hub to recruit additional endosomal protein sorting machinery (Harbour et al., 2010; Hesketh et al., 2014). The Wiskott-Aldrich syndrome protein and Scar homolog (WASH) complex mediates formation of filamentous (F)-actin and requires interaction between VPS35 and the WASH complex protein Fam21 (also known as WASHC2A) for its membrane association (Harbour et al., 2012; Jia et al., 2012; Helfer et al., 2013). VPS9-ankyrin-repeat protein (VARP, also known as ANKRD27) serves as a guanine nucleotide exchange factor (GEF) for Rab21 and an effector for Rab32 and Rab38, and binds to VPS29, targeting it to endosomes (Hesketh et al., 2014). In addition, the Rab GTPase-activating protein (GAP) TBC1D5 also requires the retromer CSC for its membrane association,
