High concentration of the EBV latent membrane protein 1 in glycosphingolipid-rich complexes from both epithelial and lymphoid cells

Latent Membrane Protein 1 (LMP1) is an EBV-transforming protein which is detected both in lymphoblastoid cell lines - resulting from EBV-immortalization in vitro - and in undifferentiated nasopharyngeal carcinoma (NPC), an EBV-associated malignancy of epithelial origin. To better define LMP1 subcellular targets, LMP1 distribution was analyzed in cellular glycosphingolipid-rich complexes (GSL-complexes) derived from epithelial and lymphoid cells. These complexes are obtained by extraction of glycosphingolipid-rich membrane domains (GSL-domains), which are clustering sites for heterotrimeric G-proteins and G-protein-associated receptors. LMP1 concentration was enriched 50-fold in GSL-complexes extracted from a NPC tumor line, C15. High concentrations of LMP1 were also observed in GSL-complexes derived from cultured lymphoid and epithelial cells. These data suggest that association with GSL-domains is an important step in LMP1 trafficking and is probably required for some aspects of its biological activity.