Abstract
The Epstein-Barr virus DNA open reading frame BALF4 (R. Baer, A.T. Bankier, M.D. Biggin, P.L. Deininger, P.J. Farrell, T.J. Gibson, G. Hatfull, G.S. Hudson, S.C. Stachwell, C. Sequin, P.S. Tuffnell, and B.G. Barrell, Nature [London] 310:207-211, 1984), which by nucleotide sequence comparison could encode a protein similar to herpes simplex virus gB (P.E. Pellett, M.D. Biggin, B. Barrell, and B. Roizman, J. Virol. 56:807-813, 1985), has now been shown to encode a 110-kilodalton glycoprotein. Late infectious cycle RNAs of 3.0 and 1.8 kilobases are transcribed from BALF4. Translation of these RNAs in vitro, transcription and translation of BALF4 in vitro, or metabolic labeling of cells in the presence of tunicamycin and immunoprecipitation with BALF4-specific sera results in identification of a 93-kilodalton precursor to gp110. Since N-glycosidase F only reduces the size of gp110 to 105 kilodaltons, gp110 probably has both N- and O-linked glycosylation, gp110 is an abundant glycoprotein in Epstein-Barr virus-infected cells. In infected lymphocytes and in 3T3 cells, in which the gene is expressed from a recombinant expression vector, most of the protein is cytoplasmic and perinuclear. In contrast to gB, gp110 was not detected in the infected-cell plasma membrane. In cells replicating Epstein-Barr virus, gp110 localized to the inner and outer nuclear membrane lamellae and to endoplasmic reticulum structures which sometimes contained enveloped virus. gp110 may play an important role in modifying infected intracellular membranes.