GSF8/PGRL/EWI-2 is a membrane protein that contains 4 Ig domains and forms highly proximal, specific and stoichiometric complexes with both CD9 and CD81 a tetraspanin. Tetraspanins and their molecular partners from primary complexes that then undergo tetraspanin-tetraspanin interactions to form a network of molecular interactions call a tetraspanin web. IGSF8 then may play a key role in diverse functions ascribed to CD81 and CD9 including oocyte fertilization or hepatitis C virus function, regulation of proliferation and differentiation of keratinocytes. It may also be a negative regulator of cell motility and suppress T-cell mobility coordinately with CD81.Synonyms: CD81 partner 3, CD81P3, EWI2, Glu-Trp-Ile EWI motif-containing protein 2, Immunoglobulin superfamily member 8, KCT4, Keratinocytes-associated transmembrane protein 4, LIR-D1