HBXAP, a novel PHD-finger protein, possesses transcription repression activity

Meir Shamay, Orr Barak, Yosef Shaul

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The PHD/LAP (plant homology domain/leukemia associated protein) finger motif is characteristically defined by a histidine and seven cysteines that are spatially arranged in a C4HC3 consensus sequence. This unique zinc finger, found primarily in a wide variety of chromatin-associated proteins, is considered to mediate protein-protein interactions. We have isolated a novel human PHD-finger protein, HBXAP (for hepatitis B virus x associated protein). HBXAP has three alternatively spliced isoforms. We also identified the Drosophila melanogaster HBXAP ortholog, gene CG8677. Based on alignment of four different proteins, we found a novel conserved domain in HBXAP that we designated the HBXAP conserved domain (XCD). We show that HBXAP represses transcription when recruited to DNA via the DNA binding of GAL4. Furthermore, the PHD finger alone suffices to repress transcription, thus attributing a functional role to this domain. The gene HBXAP is localized to the long arm of human chromosome 11 between q13.4 and q14.1. This region is amplified and rearranged in many tumors, suggesting a role for HBXAP in tumorigenesis similar to that of other PHD-containing proteins.

Original languageEnglish
Pages (from-to)523-529
Number of pages7
Issue number4
StatePublished - 2002
Externally publishedYes

Bibliographical note

Funding Information:
We thank Sylvia Budilovsky for tissue culture maintenance, Tamar Unger (both from Weizmann Institute of Science) for critical reading of the manuscript, and Ami Aronheim (Technion Israel) for the SRS two-hybrid system and the HeLa cDNA library. This research was supported by MINERVA Foundation, Germany. Y.S. holds the Oscar and Emma Getz Professorial chair.


  • Breast cancer
  • Chromosome 11q13
  • Gene amplification
  • HBV
  • HBx
  • HCC
  • PHD finger
  • XCD
  • pX


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