Guanine Nucleotide-Binding Protein Subunit Beta (GB1) Arabidopsis Thaliana Recombinant Protein

Encodes the heterotrimeric G-protein beta subunit and is involved in organ shape. A significant fraction of the protein is found in the ER. Mutants carrying null alleles express similar fruit phenotypes, as seen in er plants, but differ from er in that the stem is only slightly shorter than that in the wild type, the pedicel is slightly longer than that in the wild type, and the leaves are rounder than those in er mutants. Gene is expressed in all tissues examined, with highest expression level found in siliques. It is involved in resistance to Plectosphaerella cucumerina. The predicted protein has two DWD motifs. It can bind to DDB1a in Y2H assays and may be involved in the formation of a CUL4-based E3 ubiquitin ligase. It seems to be involved in the calcium-mediated response to extracellular ATP.

Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction. Together with GCR1 and GPA1, acts as a negative regulator of ABA during seed germination and early seedling development. The heterotrimeric G-protein controls defense responses to necrotrophic and vascular fungi probably by modulating cell wall-related genes expression (e.g. lower xylose content in cell walls); involved in resistance to fungal pathogens such as Alternaria brassicicola and Fusarium oxysporum. Modulates root architecture (e.g. lateral root formation). Acts with XGL3 in the positive regulation of root waving and root skewing. Involved in the asymmetric division of zygote and specification of apical and basal cell lineages (PubMed:27014878).