Maintains epithelial barrier function by recruiting MARVELD2/tricellulin to tricellular tight junctions (tTJs). Crucial for normal hearing by maintaining the structural and functional integrity of tTJs, which are critical for the survival of auditory neurosensory HCs. Mediates fatty acids and lipoproteins-stimulated CCK/cholecystokinin secretion in the small intestine. In the inner ear, may regulate alternative pre-mRNA splicing via binding to TRA2A, TRA2B and SRSF1. Homooligomer (By similarity). Interacts with MARVELD2 and OCLN; the interaction is required to recruit MARVELD2 to tricellular contacts. Interacts (via C-terminus) with TRA2A, TRA2B and SRSF1 (By similarity). Localizes to tricellular tight junctions (tTJs) between epithelial cells. Belongs to the immunoglobulin superfamily. LISCH7 family.