The Characteristics Of Rice U-Box Gene Family With Its Transcription And Expression Pattern Analysis

U-box domain was a high conserved motif existing in eukaryotes, especially in plants. The domain of U-box was similar to that of the RING-finger. Both of them could function as E3 ubiquitin ligase which play a key role in the recognition and selection of abnormal proteins targeted for ubiquitination and subsequent degradation, a process for the maintenances and quality control of proteins exist in living cells. In this study, a comprehensive computational analysis identified 77 U-box family genes in rice. A complete overview of this gene family in rice is presented, including the gene structures, chromosome locations, and conserved motifs. In addition, the analysis with its transcription pattern was performed by searching EST database. Epitope prediction were carried out by computer software to synthesize polypeptides. Polyclonal antibodies were generated by rabbit immunization. Western blotting analysis were carried out for rice material collected at different developmental stages to detect expression pattern. As a result of these analyses, we found U-box gene family could be divided in to 7 groups, including the group with U-box and Arm domain representing the largest class.Analysis of U-box family conserved domain in Rice found that half of the members have no introns. There are 37 members located on the 2, 4, 6 chromosome, represented 50% percent of the rice U-box family. EST analysis based on 1 million ESTs derived from 274 libraries from NCBI EST database revealed that enrichment of ESTs were found in the U-box gene with Arm domain, while not many ESTs were found in the class with only U-box domain. After all, the transcription of U-box gene in rice was significantly lower than the average of all genes. The comparison with other 16 gene families shows that the transcription level of gene family is not directly proportional to the number of family members. The family with large members has a lower transcription level. Western blotting detection of U-box protein family has two profiles, one for the constitutive expression, and the other for the tissue-specific expression. We discuss the relationship between the structure and function of the U-box family proteins based on these results and published information. It was further concluded that the expansion of the U-box family in rice might have been due to chromosomal/segmental duplication and tandem duplication. These results will be useful for future functional analyses of the U-box family genes.