A U-Box E3 Ubiquitin Ligase, PUB20, Interacts with the Arabidopsis G-Protein β Subunit, AGB1

Abstract

<div><p>An Arabidopsis U-box E3 ubiquitin ligase Plant U-box 20 (PUB20; alternatively called AtCMPG1) was identified as a possible interactor of the Arabidopsis G-protein β subunit, AGB1, by yeast two-hybrid screening. A bimolecular fluorescence complementation (BiFC) assay showed that PUB20 interacted with AGB1 in the nuclei and the cytosol. The expression levels of PUB20 and its closest homolog, PUB21 were stable under many conditions. <em>GUS</em> driven by the PUB20 promoter was active in anthers, pollen, premature seeds and receptacles and <em>GUS</em> driven by the PUB21 promoter was active in anthers and funiculi. PUB20 was found to have autoubiquitination activity <em>in vitro</em>.</p> </div