Component of the FTS/Hook/FHIP complex (FHF complex). The FHF complex may function to promote vesicle trafficking and/or fusion via the homotypic vesicular protein sorting complex (the HOPS complex). Regulates apoptosis by enhancing phosphorylation and activation of AKT1. Increases release of TNFSF6 via the AKT1/GSK3B/NFATC1 signaling cascade. FHF complex promotes the distribution of AP-4 complex to the perinuclear area of the cell. Component of the FTS/Hook/FHIP complex (FHF complex), composed of AKTIP/FTS, FHIP1B, and one or more members of the Hook family of proteins HOOK1, HOOK2, and HOOK3. Interacts directly with HOOK1, HOOK2 and HOOK3. The FHF complex associates with the homotypic vesicular sorting complex (the HOPS complex). Also interacts with AKT1. May interact with FHIP1A. Belongs to the ubiquitin-conjugating enzyme family. FTS subfamily. Lacks the conserved Cys residue necessary for ubiquitin-conjugating enzyme E2 activity.