G-PROTEIN CYCLE AND ITS PROPOSED REGULATION IN PLANTSHeterotrimeric G proteins comprising Gα,Gβ,and Gγ subunits (hereafter termed G proteins) mediate important signaling processes in all eukaryotes.As per the established paradigm,during resting phase the Gα is guanosine diphosphate (GDP)-bound and the three subunits form an inactive trimeric complex GDP· Gαβγ.Signal perception occurs at the G-protein coupled receptors (GPCRs),which act as guanine nucleotide exchange factors (GEFs) and facilitate the exchange of GDP for guanosine triphosphate (GTP) on Gα.GTP·Gα dissociates from the Gβγ dimer,and both these entities can interact with downstream effectors to transduce the signal.