UL16 Binding Brotein 3 (ULBP3)

Human cytomegalovirus (CMV) frequently infects young people and persists for the lifetime of the individual in a latent state, due in part to downregulation of major histocompatibility (MHC) class I expression and evasion of T cell-mediated immunity, with occasional asymptomatic episodes of viral shedding.  Instead of a transmembrane domain, ULBP3 has a putative glycosylphosphatidylinositol (GPI) linkage to the membrane. Enzymatic analysis confirmed that the ULBPs are indeed GPI-linked at the cell surface. RT-PCR analysis detected ULBP expression in T, B, and erythroleukemia cell lines and in a wide range of tissues. Expression was upregulated in colon and stomach tumors and downregulated in kidney tumors. FACS analysis demonstrated that protein expression generally correlated with message expression.