Vacuolar Protein Sorting 37B (VPS37B)

TSG101 bound to several different sites on VPS37B, including a putative coiled-coil region and a PTAP motif. In transfected human embryonic kidney cells, TSG101 and VPS28 coimmunoprecipitated with VPS37B, and the 3 proteins comigrated in a size-exclusion gel as a 350-kD complex, the size expected for ESCRT-I (endosomal sorting complex required for transport I). Like TSG101, VPS37B became trapped on aberrant endosomal compartments in the presence of mutant VPS4A lacking ATPase activity. VPS37B could recruit TSG101/ESCRT-I activity and thereby rescue budding of mutant human immunodeficiency virus (HIV)-1 Gag proteins or HIV-1 viruses lacking native late domains. The deduced 285-amino acid protein has an N-terminal mod(r) (modifier of rudimentary) domain that contains 2 coiled-coil motifs.