Component of the ESCRT-I complex (endosomal sorting complex required for transport I), a regulator of vesicular trafficking process. Required for the sorting of endocytic ubiquitinated cargos into multivesicular bodies (MVBs). Component of the endosomal sorting required for transport complex I (ESCRT-I), composed of ELC, VPS28 and VPS37 (By similarity). Interacts with FREE1 (PubMed:25438943). Interacts with TOL9/TOM1D (PubMed:22639582). Belongs to the ubiquitin-conjugating enzyme family. UEV subfamily.