G-proteins represent a class of molecules that can bind guanine nucleotides (GDP or GTP) and are in-volved in signal transduction. The G-protein-linked signal transduction is well established in animalswhere it is involved in biochemical events such as vision and hormone action. Plants, like animals, usesignal transduction pathways based on heterotrimeric guanine nucleotide-binding proteins (G-proteins)to regulate many aspects of developmental processes and cell signaling. Some components of G-proteinsignaling are highly conserved between plants and animals and some are not. By contrast, despite greatcomplexity in their signal-transduction attributes, plants have a simpler repertoire of G-signaling com-ponents. Nonetheless, recent studies have shown the importance of plant G-protein signaling in suchfundamental processes as cell proliferation, hormone perception and ion-channel regulation.