G-protein coupled receptors in plant cells

G-protein coupled receptors (GPCRs) are plasma membrane-spanning proteins which transduce specific physical and chemical extracellular signals into the cell. In contrast to animal cells, signal transduction pathways involving GPCRs are poorly understood in plants. However, circumstantial evidence such as the presence of G-proteins and many classical downstream signalling elements (e.g. phospholipases A2 and C) suggest that GPCR-mediated signalling operates in plant cells, in a fashion analogous to those in animal and yeast cells. In this review the evidence for plant GPCR-mediated signalling is examined. The evidence for plant G-proteins is examined at both the biochemical and molecular levels and the possible roles of plant GPCR-mediated pathways are considered. Finally, a number of strategies which may ultimately allow for the identification and characterization of plant GPCRs are presented and provide an insight into the plant signalling pathways that use this transduction mechanism.