Epstein-Barr virus-encoded protein found in plasma membranes of transformed cells.

We have developed monoclonal antibodies to a 63,000-molecular-weight protein (p63) which is the product of the most abundant messenger RNA in Epstein-Barr virus-transformed cells and shown that the protein is associated specifically with plasma membranes. It was also found to be associated with the other membrane fractions and was found in all Epstein-Barr virus-transformed cells tested. In addition, p63 was present in virions, resulting in transient, early appearance in newly infected cells. Newly synthesized p63 was detected at the time cells underwent blast transformation (48 to 72 h postinfection). The possible role of this protein in transformation and as a target for cell-mediated cytotoxicity is discussed.