Probably involved in vesicular trafficking via its association with the CART complex (PubMed:15772161). The CART complex is necessary for efficient transferrin receptor recycling but not for EGFR degradation (PubMed:15772161). Positively regulates motility of microtubule-dependent motor protein KIF21B (By similarity). Associates with myosin-Vb (MYO5B) and alpha-actinin-4 (ACTN4) (By similarity). Component of the CART complex, at least composed of ACTN4, HGS/HRS, MYO5B and TRIM3 (PubMed:15772161). Interacts with ZFYVE28/LST2 (PubMed:19460345). Interacts with KIF21B (By similarity). Expressed in brain, heart, uterus and testis. The interaction with MYO5B is dependent upon its NHL repeats, which form a beta-propeller (NHL) domain containing six blades. Belongs to the TRIM/RBCC family.