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标题：GTPase acceleration as the rate-limiting step in Arabidopsis G protein-coupled sugar signaling
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作者：Christopher A. Johnston ; J. Philip Taylor ; Yajun Gao 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2007
卷号：104
期号：44
页码：17317-17322
DOI：10.1073/pnas.0704751104
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Heterotrimeric G protein signaling is important for cell-proliferative and glucose-sensing signal transduction pathways in the model plant organism Arabidopsis thaliana. AtRGS1 is a seven-transmembrane, RGS domain-containing protein that is a putative membrane receptor for D-glucose. Here we show, by using FRET, that D-glucose alters the interaction between the AtGPA1 and AtRGS1 in vivo. AtGPA1 is a unique heterotrimeric G protein {alpha} subunit that is constitutively GTP-bound given its high spontaneous nucleotide exchange coupled with slow GTP hydrolysis. Analysis of a point mutation in AtRGS1 that abrogates GTPase-accelerating activity demonstrates that the regulation of AtGPA1 GTP hydrolysis mediates sugar signal transduction during Arabidopsis development, in contrast to animals where nucleotide exchange is the limiting step in the heterotrimeric G protein nucleotide cycle.
关键词：d-glucose ; G protein-coupled receptor ; guanine nucleotide cycle ; RGS protein ; GTPase-accelerating protein