Hepatitis B virus X protein interacts with β5 subunit of heterotrimeric guanine nucleotide binding protein

Background: To isolate cellular proteins interacting with hepatitis B virus X protein (HBX), from HepG2 cells infected with hepatitis B virus (HBV). Results: HBV particles were produced in culture medium of HepG2 cells transfected with the mammalian expression vector containing the linear HBV genome, as assessed by commercially available ELISA assay. A cDNA library was made from these cells exposed to HBV. From yeast two hybrid screening with HBX as bait, human guanine nucleotide binding protein β subunit 5L (GNβ5) was isolated from the cDNA library constructed in this study as a new HBX-interacting protein. The HBX-GNβ5 interaction was further supported by mammalian two hybrid assay. Conclusion: The use of a cDNA library constructed from HBV-transfected HepG2 cells has resulted in the isolation of new cellular proteins interacting with HBX.