PROSITE documentation PDOC51310

VPS28 C-terminal domain profile

The endosomal sorting complex I required for transport (ESCRT-I) is composed of the three subunits VPS23/TSG101, VPS28 and VPS37. ESCRT-I is recruited to cellular membranes during multivesicular endosome biogenesis and by enveloped viruses such as HIV-1 to mediate budding from the cell. The C-terminal domain of VPS28 is characterized by a high-sequence conservation throughout all kingdoms of life. It does not directly participate in ESCRT-I assembly (see <PDOC51312>) but serves as an adaptor module linked to the ESCRT-I complex that connects its function to other components of the VPS machinery, including ESCRT-III VPS20 [1].

The VPS28 C-terminal domain folds independently into a four-helical bundle structure with N- and C-terminal ends juxtaposed to each other (see <PDB:2G3K>). Helices 1, 2 and 4 have the same length, while helix 3 is shorter and packs with an approximate angle of 45 degrees against the remaining three helices. The connecting loop regions between helices 1 and 2 and helices 2 and 3 are short compared with the longer well-ordered loop connecting helices 3 and 4. Because this loop contains a conserved sequence motif, it may be involved in protein-protein interactions [1].

The profile we developed covers the entire VPS28 C-terminal domain.