Classification, expression pattern, and E3 Ligase Activity Assay of Rice U-box-containing proteins

Li Rong Zeng, Chan Ho Park, R. C. Venu, Julian Gough, Guo Liang Wang

Research output: Contribution to journalArticlepeer-review

128 Scopus citations


Ubiquitin ligases play a central role in determining the specificity of the ubiquitination system by selecting a myriad of appropriate candidate proteins for modification. The U-box is a recently identified, ubiquitin ligase activityrelated protein domain that shows greater presence in plants than in other organisms. In this study, we identified 77 putative U-box proteins from the rice genome using a battery of whole genome analysis algorithms. Most of the U-box protein genes are expressed, as supported by the identification of their corresponding expressed sequence tags (ESTs), full-length cDNAs, or massively parallel signature sequencing (MPSS) tags. Using the same algorithms, we identified 61 U-box proteins from the Arabidopsis genome. The rice and Arabidopsis U-box proteins were classified into nine major classes based on their domain compositions. Comparison between rice and Arabidopsis U-box proteins indicates that the majority of rice and Arabidopsis U-box proteins have the same domain organizations. The inferred phylogeny established the homology between rice and Arabidopsis U-box/ARM proteins. Cell death assay using the rice protoplast system suggests that one rice U-box gene, OsPUB51, might act as a negative regulator of cell death signaling. In addition, the selected U-box proteins were found to be functional E3 ubiquitin ligases. The identification and analysis of rice U-box proteins hereby at the genomic level will help functionally characterize this class of E3 ubiquitin ligase in the future.

Original languageEnglish (US)
Pages (from-to)800-815
Number of pages16
JournalMolecular Plant
Issue number5
StatePublished - Sep 2008
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Plant Science


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