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Journal of Virology, December 2005, p. 15525-15536, Vol. 79, No. 24
0022-538X/05/$08.00+0 doi:10.1128/JVI.79.24.15525-15536.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Signal Peptide Cleavage and Internal Targeting Signals Direct the Hepatitis C Virus p7 Protein to Distinct Intracellular Membranes
Stephen Griffin,
Dean Clarke,
Christopher McCormick,
David Rowlands, and
Mark Harris*
Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
Received 8 February 2005/
Accepted 30 August 2005
The hepatitis C virus (HCV) p7 protein forms an amantadine-sensitive ion channel required for viral replication in chimpanzees, though its precise role in the life cycle of HCV is unknown. In an attempt to gain some insights into p7 function, we examined the intracellular localization of p7 using epitope tags and an anti-p7 peptide antibody, antibody 1055. Immunofluorescence labeling of p7 at its C terminus revealed an endoplasmic reticulum (ER) localization independent of the presence of its signal peptide, whereas labeling the N terminus gave a mitochondrial-type distribution in brightly labeled cells. Both of these patterns could be visualized within individual cells, suggestive of separate pools of p7 where the N and C termini differed in accessibility to antibody. These patterns were disrupted by preventing signal peptide cleavage. Subcellular fractionation revealed that p7 was enriched in a heavy membrane fraction associated with mitochondria as well as normal ER-derived microsomes. The complex regulation of the intracellular distribution of p7 suggests that p7 plays multiple roles in the HCV life cycle either intracellularly or as a virion component.
* Corresponding author. Mailing address: Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom. Phone: 44 (113) 343-5632. Fax: 44 (113) 343-5638. E-mail:
m.harris{at}leeds.ac.uk.
Present address: Molecular Biology, University of Southampton, Southampton SO16 6 YD, United Kingdom.
Journal of Virology, December 2005, p. 15525-15536, Vol. 79, No. 24
0022-538X/05/$08.00+0 doi:10.1128/JVI.79.24.15525-15536.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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