Poster: Intracellular Signaling
Abs #
834: Isolation and characterization of OsGCR1 encoding a putative G protein-coupled receptor in rice
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Presenter: |
Kato, Hisaharu , vtec@fpu.ac.jp |
Authors | Kato, Hisaharu (A) Oki, Katsuyuki (A) Yamamoto, Shyuhei (A) Fujisawa, Yukiko (A) Iwasaki, Yukimoto (A) | | Affiliations: |
(A): Dept. Biosci., Fac. Biotech., Fukui Prefectural Univ.
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Heterotrimeric G proteins, composed of a-, b- and g-subunits, play a crucial role in plant development. In the case of rice, d1 mutant lacking the a subunit shows abnormal morphology, such as dwarfism, dark green leaf and small round grain, and partially impaired responsiveness to gibberellin. Although reports concerning each subunit in plants are gradually increasing, there is little information about other components involved in the G protein-mediated signaling in plants. There are more than 1000 G protein-coupled receptors (GPCRs) estimated to exist in mammals, but, only a single gene, GCR1, encoding a putative GPCR derived from Arabidopsis has been characterized in plants.
To dissect the molecular mechanisms of the G protein-mediated signaling in rice, we have cloned and sequenced a rice cDNA homologue of GCR1 (OsGCR1). OsGCR1 encoded a 321 amino acid polypeptide which showed 63.2% amino acid identity to the GCR1. Hydropathy plot analysis indicated a protein topology consisting of 7 potential transmembrane spanning domains that is a structure characteristic of GPCRs. Amino acid sequence alignment showed conservation of several important amino acid residues that are found in a number of GPCRs, but no extracellular N-linked glycosylation site was identified. RNA gel blot analysis using poly (A)+ RNA showed that the transcript level of OsGCR was high in seedling, internode and ear tissue before heading and low in root and ear tissue after heading. To determine the subcellular localization of OsGCR1, we constructed CaMV 35S promoter-OsGCR1-GFP and introduced into onion epidermal cells by using particle bombardment. Cells expressing the construct showed a cell surface staining image, demonstrating that OsGCR1 is localized at the plasma membrane.
