Related Experiment Video
Updated: Jun 28, 2026

Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle
Published on: February 1, 2017
Characterization of the nuclear localization signal of the hepatitis delta virus antigen
Carolina Alves1, Natália Freitas, Celso Cunha
1Unidade de Biologia Molecular, Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 96 1349-008 Lisboa, Portugal.
Abstract:
The delta antigen (HDAg) is the only protein encoded by the hepatitis delta virus (HDV) RNA genome. The HDAg contains an RNA binding domain, a dimerization domain, and a nuclear localization signal (NLS). The nuclear import of HDV RNPs is thought to be one of the first tasks of the HDAg during the HDV replication cycle. Using c-myc-PK fusions with several regions of the HDAg in transfection assays in Huh7 cells, we found that the HDAg NLS consists of a single stretch of 10 amino acids, EGAPPAKRAR, located in positions 66-75. Deletion and mutation analysis of this region showed that both the acidic glutamic acid residue at position 66 and the basic arginine residue at position 75 are essential for promoting nuclear import.
Related Concept Videos
Nuclear Protein Sorting
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Nuclear Localization Signals and Import
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Regulation of Nuclear Protein Sorting
Hepatitis
Viral Hepatitis I: Introduction

