More (G-proteins) please! Identification of an elaborate network of G-proteins in soybean.

The studies performed in model plants Arabidopsis and rice have revealed a significantly simple repertoire of canonical G-protein components in plants, with the presence of only two possible heterotrimers versus hundreds of possible trimeric combinations in animal systems. Since a number of plant species are polyploid, we assessed if genome duplication events have resulted into multiplicity of G-protein components in such plants and whether the duplicated gene pairs have specific expression patterns or biochemical properties. Our analysis of soybean genome has identified four Gα, four Gβ and two Gγ proteins, predicting thirty-two possible heterotrimeric combinations. All ten G-protein genes are retained in soybean genome and ubiquitously expressed. The G-protein genes have interesting expression profiles during seed developments and germination. The four Gα proteins form two distinct groups based on their GTPase activity. Yeast-based interaction analyses predict that the proteins interact in most but not all of the possible combinations, and there is some degree of interaction specificity between duplicated gene pairs. This research, thus, identifies the most elaborate heterotrimeric G-protein network known to date in plants.