X protein of hepatitis B virus resembles a serine protease inhibitor.
The X protein of hepatitis B virus (HBV) has been shown to be a trans-activator for viral and cellular genes. Amino acid sequences in X protein were found to be highly homologous to functionally essential sequences in the "Kunitz domain," characteristic of Kunitz-type serine protease inhibitors. Mutations at these sequences completely abolished trans-activation. Consequently, HBV X protein resembles a serine protease inhibitor or its analogue, and may bring about trans-activation by activating certain transcriptional factors through proteolytic cleavage alteration.
Takada
S
S
Department of Gene Research, Cancer Institute, Tokyo.
Koike
K
K
D000595:Amino Acid Sequence; D005814:Genes, Viral; D006515:Hepatitis B virus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*; D015534:Trans-Activators / Q000032:analysis / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
D015842:Serine Proteinase Inhibitors; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein