ESCRT complexes form the main machinery driving protein sorting from endosomes to lysosomes. The core domain of the Vps23 subunit of the heterotrimeric ESCRT-I complex is a helical hairpin sandwiched in a fan-like formation between two other helical hairpins from Vps28 (Pfam:PF03997) and Vps37. Vps23 gives ESCRT-I complex its stability [1].

1: ESCRT-I core and ESCRT-II GLUE domain structures reveal role for GLUE in linking to ESCRT-I and membranes. Teo H, Gill DJ, Sun J, Perisic O, Veprintsev DB, Vallis Y, Emr SD, Williams RL; Cell. 2006;125:99-111. PMID:16615893