Probable role in the clearance of triglyceride-rich lipoprotein from blood. Binds chylomicrons, LDL and VLDL in presence of free fatty acids and allows their subsequent uptake in the cells (By similarity). Maintains epithelial barrier function by recruiting MARVELD2/tricellulin to tricellular tight junctions (By similarity). Homotrimer or homotetramer (By similarity). Assembles into cell-cell contacts. Interacts (via the cytoplasmic domain) with MARVELD2 (via C-terminal cytoplasmic domain); the interaction is required to recruit MARVELD2 to tricellular contacts. Interacts with OCLN (By similarity). Located at tricellular contacts. Phosphorylation at Ser-365 by MAPK8/JNK1 and MAPK9/JNK2 may be required for exclusive localization at tricellular tight junstions. Belongs to the immunoglobulin superfamily. LISCH7 family. In contrast to the rodent orthologous protein, it is longer in N-terminus and no signal sequence is detected by any prediction method. Extended N-terminus.