Transcriptional involvement of the Hepatitis B Virus Protein in Cellular Transduction Systems. Protein-Protein Interactions with Bzip transactivators
The Hepatitis B virus genome is 3.2 Kb and contains fourrecognized open reading frames, three of which encode virion structural proteins, Tiollais et al. (1985). These include the S gene (surface antigen), the C-gene (core antigen) and the viral polymerase. The fourth open reading frame, which is conserved among all mammalian hepadnaviruses, encodes a 16.5 KDa protein, termed X antigen. The X gene product is expressed during viral infection, producing a 1Kb mRNA, Tiollais et al. (1985). Direct evidence for the ability of the X gene to encode a protein has been obtained by its expression in both prokaryotic, Moriarty et al. (1985) and eukaryotic systems, Kay et al. (1985). The importance of the X gene product in viral infection has been demonstrated by frameshift X mutants of ground squirrel hepatitis virus, which failed to grow in animal hosts, Siddiqui et al. (1987). Recent evidence obtained from transgenic animal experiments supports the role of the HBV X gene product in the development of hepatocellular carcinomas, Kim et al. (1991), although its mechanism is currently unknown.
KeywordsPC12 Cell Leucine Zipper Transcription Factor CREB Cellular Transcription Factor CREB Protein
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