Abstract
Liver specificity of hepatitis B virus (HBV) replication has been attributed to the action of its second enhancer (EII). We report here the characterization of EII and the subsequent isolation of a novel liver-specific DNA-binding protein which binds to and activates EII. The cDNA clone of the protein, designated E2BP, was isolated from a lambda gt11 expression library constructed from the hepatoma cell line HuH-6 which was screened with a binding site probe derived from EII. Sequence analysis of E2BP revealed 86.6% homology with a rat heterogeneous nuclear ribonucleoprotein C protein sequence, while conformational studies suggest a helix-loop-helix motif as a DNA-binding site. Cloned E2BP expressed in human fibroblasts by transient transfection displayed EII binding and activating characteristics similar to those of native E2BP in hepatocytes.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Blotting, Northern
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Cell Line
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Cells, Cultured
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Chloramphenicol O-Acetyltransferase / genetics
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Chloramphenicol O-Acetyltransferase / metabolism
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Cloning, Molecular
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism*
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Enhancer Elements, Genetic*
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Hepatitis B virus / genetics*
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Heterogeneous-Nuclear Ribonucleoproteins
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Humans
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Liver / microbiology*
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Molecular Sequence Data
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Oligodeoxyribonucleotides
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Open Reading Frames
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Plasmids
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Promoter Regions, Genetic
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RNA, Heterogeneous Nuclear / metabolism
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RNA, Messenger / genetics
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RNA, Messenger / isolation & purification
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RNA, Messenger / metabolism
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Ribonucleoproteins / genetics*
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Ribonucleoproteins / metabolism*
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Sequence Homology, Amino Acid
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Sequence Homology, Nucleic Acid
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Trans-Activators / genetics*
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Trans-Activators / metabolism*
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Transcription, Genetic*
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Transfection
Substances
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DNA-Binding Proteins
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Heterogeneous-Nuclear Ribonucleoproteins
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Oligodeoxyribonucleotides
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RNA, Heterogeneous Nuclear
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RNA, Messenger
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Ribonucleoproteins
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Trans-Activators
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Chloramphenicol O-Acetyltransferase