This family represents a conserved region approximately 150 residues long within a number of eukaryotic proteins that show homology with Drosophila melanogaster Modifier of rudimentary (Mod(r)) proteins. The N-terminal half of Mod(r) proteins is acidic, whereas the C-terminal half is basic, and both of these regions are represented in this family. Members of this family include the Vps37 subunit of the endosomal sorting complex ESCRT-I, a complex involved in recruiting transport machinery for protein sorting at the multivesicular body (MVB). The yeast ESCRT-I complex consists of three proteins (Vps23, Vps28 and Vps37). The mammalian homolog of Vps37 interacts with Tsg101 (pfam05743) through its mod(r) domain and its function is essential for lysosomal sorting of EGF receptors.