Proteome-Wide Computational Analysis for More G Protein-Coupled Receptors-Like Proteins in Selected Plants

G protein-coupled receptor (GPCR), superfamily of heptahelical transmembrane receptor proteins, controls a plethora of signals through either interaction with G protein heterotrimer or independent of G protein. Unlike animals possessing a considerable number of canonical GPCRs and their cognate heterotrimeric G-protein components for signal perception and transduction, plants have a relatively simple repertoire of G proteins. Although the functional cooperativity of plant G-proteins with heptahelical transmembrane receptor-like proteins as Arabidopsis Regulators of G Protein Signalling (RGS۱) is established, the presence of canonical GPCR is arguable. However, genome duplication events and polyploidy levels in several plants suggest the presence of several heptahelical transmembrane receptor-like proteins with analogous biochemical features. A high degree of sequence diversity and limited proteome data pose major bottlenecks associated with the identification of GPCR(s). We have identified eight, three, one, and three canonical GPCR-like proteins in Arabidopsis thaliana, Glycine max, Sorghum bicolor, and Zea mays, respectively. Similarly, we have also identified ۲۵ (At:۳, Gm:۱۳, Sb:۳, and Zm:۶) uncanonical GPCR-like proteins that do not interact with G protein α subunit (Gα) but are analogous to various GPCRs of different signalling pathways. Identified high probability GPCR-like plant proteins have all signature motifs and functional characteristic features of the canonical GPCR. Current findings provide an insight into the diversity, distribution, and conservation of candidate GPCRs in plants.

Keywords:

Canonical GPCR , G Protein-coupled receptor , heterotrimeric G protein , Heptahelical transmembrane protein , self-activating Gα , uncanonical GPCR