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PARTIAL CHARACTERIZATION and LIGHT‐INDUCED REGULATION OF GTP‐BINDING PROTEINS IN Lemna paucicostata
Author(s) -
Hasunuma Kohji,
Furukawa Kazuhiko,
Funadera Kanako,
Kubota Mamoru,
Watanabe Masakatsu
Publication year - 1987
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1987.tb04807.x
Subject(s) - gtp' , lemna , darkness , pertussis toxin , g protein , biochemistry , size exclusion chromatography , chemistry , binding protein , biology , biophysics , receptor , botany , enzyme , gene
Binding of GTP‐binding proteins with [ 35 S]GTP7S in the extract containing membrane components of Lemna paucicostata 441 was inhibited by red or far red light by 20 to 25%, but blue light showed no or little effect. The plant used for the preparation of the extract was subjected to single darkness for 8 h, as both red and far red light inhibit flowering. The extract treated with 1% Lubrol was fractionated by gel filtration. Four species of GTP‐binding proteins, GL1, GL2, GL3 and GL4 were detected with Km values 3, 7, 80 and 4 n M , respectively. GL1, GL2 and GL3 were ADP‐ribosylated by pertussis toxin. The extract activated by [ 35 S]GTP‐γS in darkness, under red light or under far red light was treated with 1% Lubrol and subsequent gel filtration of the extracts made it possible to detect GTP‐binding protein with a small molecular weight only in an extract labeled in darkness. The reduction in the molecular weight of GTP‐binding protein from the larger molecule associated with the binding of [ 35 S]GTPγS was confirmed by rechromatography of the larger molecule activated by [ 35 S]GTPγS in darkness. The binding of GL2 and/or GL3 with [ 35 S]GTPγS was suggested to be inhibited by red or far red light.