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. 1996 Dec 1;24(23):4741–4750. doi: 10.1093/nar/24.23.4741

XAP2, a novel hepatitis B virus X-associated protein that inhibits X transactivation.

N Kuzhandaivelu 1, Y S Cong 1, C Inouye 1, W M Yang 1, E Seto 1
PMCID: PMC146319  PMID: 8972861

Abstract

The hepatitis B virus X protein is a promiscuous transcriptional transactivator. Transactivation by the X protein is most likely mediated through binding to different cellular factors. Using the yeast two-hybrid method, we have isolated a clone that encodes a novel X-associated cellular protein: XAP2. X and XAP2 interactions also occur in vitro. Antiserum raised against XAP2 recognizes a cytoplasmic protein with an apparent molecular mass of 36 kDa. The interaction between X and XAP2 requires a small region on X containing amino acids 13-26. From Northern blot analyses, XAP2 is ubiquitously expressed in both liver-derived and non-liver-derived cell lines as well as in normal non-liver tissues. In contrast, XAP2 is expressed in very low level in the normal human liver. In transfection assays, overexpression of XAP2 abolishes transactivation by the X protein. Based on these results, we suggest that XAP2 is an important cellular negative regulator of the X protein, and that X-XAP2 interaction may play a role in HBV pathology.

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Selected References

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