title: HBx protein of hepatitis B virus interacts with the C-terminal portion of a novel human proteasome alpha-subunit.
abstract: Two-hybrid protein interaction screening in yeast was used to identify proteins that interact with the HBx nonstructural protein of hepatitis B virus (HBV). A new human member of the proteasome alpha-subunit family was obtained. Its protein sequence closely resembles the 28 kD subunits from other organisms. The interaction with HBx was abolished by a two amino-acid insertion behind position 128 in HBx, in a region previously found to be essential for its transcriptional transactivation function. These data support a model of HBx acting indirectly on transcriptional processes. By binding to a specific proteasome alpha-subunit, HBx might interfere with degradative processes, thereby enhancing the half-life of different transcription factors and other nuclear regulatory proteins. Interaction with the Hu 28k proteasome subunit could thus provide a unifying explanation for the markedly pleiotropic effects of HBx.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006367:HeLa Cells; D006511:Hepatitis B Antigens / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D006511:Hepatitis B Antigens; D009097:Multienzyme Complexes; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex