Disease relevance of GCR1

• Transgenic Arabidopsis expressing antisense GCR1 under the control of the constitutive cauliflower mosaic virus 35S promoter have reduced sensitivity to cytokinins in roots and shoots, yet respond normally to all other plant hormones [1].

High impact information on GCR1

• However, whether GCR1 actually interacts with GPA1 was unknown [2].
• These data are consistent with the hypothesis that GCR1 may be a regulator of the cell cycle and that this regulation underlies the developmental changes observed in the GCR1 transformants [3].
• Overexpression of GCR1 in Arabidopsis caused two remarkable phenotypes: seed dormancy was abolished and time to flowering was reduced [3].
• Overexpression of GCR1 in tobacco (Nicotiana tabacum) BY-2 cells caused an increase in thymidine incorporation and in the mitotic index of aphidicolin synchronized cells [3].
• This suggests a functional role for GCR1 in cytokinin signal transduction [1].

Biological context of GCR1

• RESULTS: Using information in the dbEST database of expressed sequence tags, we isolated an Arabidopsis thaliana gene (GCR1) that encodes a protein with seven predicted membrane-spanning domains and other features characteristic of 7TM receptors [1].
• GCR1 is expressed at very low levels in the roots, stems and leaves of Arabidopsis; it is a single-copy gene which maps close to the restriction fragment length polymorphism marker m291 on chromosome 5 [1].
• Insertion mutagenesis confirms that GPA1 and the sole canonical G-protein-coupled receptor (GCR1) in Arabidopsis also have a role in this blue light-mediated event [4].

Anatomical context of GCR1

• The cast of Ca(2+) sensors includes the well-characterized extracellular-Ca(2+)-sensing receptor, a G-protein-coupled receptor originally isolated from the parathyroid gland [5].

Associations of GCR1 with chemical compounds

• Our data show that GPA1, AGB1, and GCR1 each negatively regulates ABA signaling in seed germination and early seedling development [6].
• Using a variety of approaches, we show here that GCR1-enhanced thymidine incorporation into DNA depends on an increase in phosphatidylinositol-specific phospholipase C activity and an elevation of inositol 1,4,5-trisphosphate levels in the cells [7].
• The Arabidopsis putative G protein-coupled receptor GCR1 interacts with the G protein alpha subunit GPA1 and regulates abscisic acid signaling [2].
• G-protein-coupled receptor 1, G-protein Galpha-subunit 1, and prephenate dehydratase 1 are required for blue light-induced production of phenylalanine in etiolated Arabidopsis [4].

Other interactions of GCR1

• We demonstrate by in vitro pull-down assays, by yeast split-ubiquitin assays, and by coimmunoprecipitation from plant tissue that GCR1 and GPA1 are indeed physically coupled [2].
• This protein has the predicted topology and structure of a G-protein-coupled receptor in that it contains seven transmembrane domains, but AtRGS1 also contains a unique C-terminal extension, namely a regulator of G-protein signaling domain (RGS box) [8].

References