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The human I-mfa domain containing protein, HIC, interacts with HIV-1 Tat and Rev and sequesters them in the cytoplasm

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Tat and Rev are equally critical for HIV-1 replication and work in a sequential manner: first, transactivation of the HIV-1 LTR by Tat, followed by nuclear export of partially spliced and unspliced viral transcripts by Rev. Both functions require Tat and Rev to be imported to the nucleus, a process mediated by molecular recognition of their homologous arginine-rich NLS domains by importin-β.

Here, we report the interaction of the human I-mfa domain containing protein, HIC, with Tat and Rev resulting in the cytoplasmic redistribution of Tat and Rev with a concomitant reduction in their nuclear accumulation. We will discuss our data resulting from colocalisation studies and competitive in vitro nuclear import assays, which collectively support a model where HIC would mask Tat and Rev NLS domains, thereby impairing their nuclear import via rendering the NLS inaccessible to importin-β.

Functionally, this cytoplasmic sequestration could appear to represent a novel mechanism for the control of Tat and Rev activities and ultimately the regulation of HIV-1 replication.

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Correspondence to L Gu.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Infectious Disease
  • Cancer Research
  • Molecular Recognition
  • Nuclear Export
  • Nuclear Import