Acts as a component of the WASH core complex that functions as a nucleation-promoting factor (NPF) at the surface of endosomes, where it recruits and activates the Arp2/3 complex to induce actin polymerization, playing a key role in the fission of tubules that serve as transport intermediates during endosome sorting. Mediates the recruitment of the WASH core complex to endosome membranes via binding to phospholipids and VPS35 of the retromer CSC. Mediates the recruitment of the F-actin-capping protein dimer to the WASH core complex probably promoting localized F-actin polymerization needed for vesicle scission. Via its C-terminus binds various phospholipids, most strongly phosphatidylinositol 4-phosphate (PtdIns-(4)P), phosphatidylinositol 5-phosphate (PtdIns-(5)P) and phosphatidylinositol 3,5-bisphosphate (PtdIns-(3,5)P2). Involved in the endosome-to-plasma membrane trafficking and recycling of SNX27-retromer-dependent cargo proteins, such as GLUT1. Required for the association of DNAJC13, ENTR1, ANKRD50 with retromer CSC subunit VPS35. Required for the endosomal recruitment of CCC and retriever complexes subunits COMMD1 and CCDC93 as well as the retrievere complex subunit VPS35L. Component of the WASH core complex also described as WASH regulatory complex (SHRC) composed of WASHC1, WASHC2, WASHC3, WASHC4 and WASHC5; in the complex interacts (via N-terminus) directly with WASHC1. The WASH core complex associates with the F-actin-capping protein dimer (formed by CAPZA1, CAPZA2 or CAPZA3 and CAPZB) in a transient or substoichiometric manner which was initially described as WASH complex. Interacts with VPS35; mediates the association with the retromer CSC complex. Interacts with FKBP15. Interacts with CCDC93, CCDC22, VPS35L; indicative for an association of the WASH core complex with the CCC and retriever complexes (By similarity). Directly interacts with TBC1D23 (By similarity). The LFa (leucine-phenylalanine-acidic) motif bind directly to VPS35 of retromer CSC; adjacent motifs can act cooperatively to bind multiple CSCs, although there is significant variability in the affinities of different motifs for retromer. Belongs to the FAM21 family.