Plays a role in vesicle-mediated protein trafficking of the endocytic membrane transport pathway. Believed to act as a component of the putative CORVET endosomal tethering complexes which is proposed to be involved in the Rab5-to-Rab7 endosome conversion probably implicating MON1A/B, and via binding SNAREs and SNARE complexes to mediate tethering and docking events during SNARE-mediated membrane fusion. The CORVET complex is proposed to function as a Rab5 effector to mediate early endosome fusion probably in specific endosome subpopulations (PubMed:25266290). Functions predominantly in APPL1-containing endosomes (PubMed:25266290). Interacts with RAB5C (By similarity). Interacts with TGFBRAP1 (PubMed:25266290). Component of the putative class C core vacuole/endosome tethering (CORVET) complex; the core of which composed of the class C Vps proteins VPS11, VPS16, VPS18 and VPS33A, is associated with VPS8 and TGFBRAP1 (PubMed:25266290). Belongs to the VPS8 family. Truncated N-terminus.