title: EXTRA-LARGE G PROTEINs Interact with E3 Ligases PUB4 and PUB2 and Function in Cytokinin and Developmental Processes.
abstract: Heterotrimeric GTP-binding proteins (G proteins) composed of Gα, Gβ, and Gγ subunits are conserved signal transduction molecules in animals and plants. In Arabidopsis (Arabidopsis thaliana), there are three Gα-like proteins named EXTRA-LARGE G PROTEINs (XLGs) in addition to the canonical Gα protein GPA1. XLGs have been reported to be implicated in multiple pathways, although the underlying mechanisms of their action remain elusive. Here, we report that all three XLGs interact with two closely related plant U-box (PUB) E3 ligases, PUB2 and PUB4. Three XLGs are predominantly localized at the plasma membrane, whereas XLG2 and XLG3 also show nuclear localization. The interactions between PUB2/4 and XLGs suggest that they might function in the same pathways. Indeed, we found that a newly obtained xlg1/2/3 triple knockout mutant, the pub4 mutant, and the pub2/4 double mutant all exhibited defects in cytokinin responses, stamen development, tapetum development, and male fertility. However, the xlg single mutants and the pub2 mutant did not exhibit an obvious defect in these processes, which suggests functional redundancy among the three XLGs and between PUB2 and PUB4. Overexpressing ARR10 to enhance the cytokinin response in pub4 or in the xlg1/2/3 triple mutant partially restored several phenotypes caused by the pub4 and xlg1/2/3 mutations. Our findings reveal that the XLGs and PUB2/4 are components in the complex cytokinin signaling networks regulating many developmental and physiological processes.
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China (Y. Wang, Y. Wu, B.Y., Z.Y., Y.X.); and.|Partner State Key Laboratory of Agricultural Biotechnology, Chinese University of Hong Kong, Hong Kong, China (Y.X.).
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China (Y. Wang, Y. Wu, B.Y., Z.Y., Y.X.); and.|Partner State Key Laboratory of Agricultural Biotechnology, Chinese University of Hong Kong, Hong Kong, China (Y.X.).
authors.forename: Yingying
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China (Y. Wang, Y. Wu, B.Y., Z.Y., Y.X.); and.|Partner State Key Laboratory of Agricultural Biotechnology, Chinese University of Hong Kong, Hong Kong, China (Y.X.).
authors.forename: Boying
authors.initials: B
authors.lastname: Yu
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China (Y. Wang, Y. Wu, B.Y., Z.Y., Y.X.); and.|Partner State Key Laboratory of Agricultural Biotechnology, Chinese University of Hong Kong, Hong Kong, China (Y.X.).
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yin
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China (Y. Wang, Y. Wu, B.Y., Z.Y., Y.X.); and yxia@hkbu.edu.hk.|Partner State Key Laboratory of Agricultural Biotechnology, Chinese University of Hong Kong, Hong Kong, China (Y.X.) yxia@hkbu.edu.hk.
authors.forename: Yiji
authors.identifier: 0000-0002-9543-8341
authors.initials: Y
authors.lastname: Xia
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D030821:Plants, Genetically Modified; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: C469257:ARR10 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; C120055:XLG1 protein, Arabidopsis; C000623001:PUB2 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins; C527829:XLG2 protein, Arabidopsis; C527830:XLG3 protein, Arabidopsis; C000596069:PUB4 protein, Arabidopsis