Identification and cloning of a novel heterogeneous nuclear ribonucleoprotein C-like protein that functions as a transcriptional activator of the hepatitis B virus enhancer II. |
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| Authors: | N Tay S H Chan E C Ren |
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| Affiliation: | W.H.O. Collaborating Centre for Immunology, Faculty of Medicine, National University of Singapore. |
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| 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. |
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