Putative Rab GTPase-activating protein which plays a role in vesicular trafficking. Involved in endosome-to-Golgi trafficking. Acts as a bridging protein by binding simultaneously to golgins, including GOLGA1 and GOLGA4, located at the trans-Golgi, and to the WASH complex, located on endosome-derived vesicles (PubMed:29084197). Together with WDR11 complex facilitates the golgin-mediated capture of vesicles generated using AP-1 (By similarity). Plays a role in brain development, including in cortical neuron positioning. May also be important for neurite outgrowth, possibly through its involvement in membrane trafficking and cargo delivery, 2 processes which are essential for axonal and dendritic growth (PubMed:28823707). May act as a general inhibitor of innate immunity signaling, strongly inhibiting multiple TLR and dectin/CLEC7A-signaling pathways. Does not alter initial activation events, but instead affects maintenance of inflammatory gene expression several hours after bacterial lipopolysaccharide (LPS) challenge (PubMed:22312129). Directly interacts with GOLGA1 and GOLGA4 (PubMed:29084197). Interacts with FAM91A1, C17ORF75 and WDR11; the interaction recruits TBC1D23 to AP-1-derived vesicles (PubMed:29084197). Directly interacts with WASHC1 and WASHC2/FAM21 (PubMed:29084197). Interacts with FKBP15 (PubMed:29084197). Localization to the trans-Golgi (TGN) is regulated by ARL1 and ARL5B/ARL8. ARL1 increases Golgi localization, while ARL5B decreases it. Recruitment to the trans-Golgi network requires the presence of GOLGA1 and GOLGA4, but not that of FAM91A1 (By similarity). Recruited on AP-1-derived vesicles by WDR11 complex (By similarity). Mutant mice exhibit increased inflammatory cytokine production and recruit more inflammatory cells to the peritoneum, when challenged with different pathogen-associated molecular patterns (PAMPs), including LPS.