title: RPT2 is a signal transducer involved in phototropic response and stomatal opening by association with phototropin 1 in Arabidopsis thaliana.
abstract: Phototropin 1 (phot1) and phot2, which are blue light receptor kinases, function in blue light-induced hypocotyl phototropism, chloroplast relocation, and stomatal opening in Arabidopsis (Arabidopsis thaliana). Previous studies have shown that the proteins RPT2 (for ROOT PHOTOTROPISM2) and NPH3 (for NONPHOTOTROPIC HYPOCOTYL3) transduce signals downstream of phototropins to induce the phototropic response. However, the involvement of RPT2 and NPH3 in stomatal opening and in chloroplast relocation mediated by phot1 and phot2 was unknown. Genetic analysis of the rpt2 mutant and of a series of double mutants indicates that RPT2 is involved in the phot1-induced phototropic response and stomatal opening but not in chloroplast relocation or phot2-induced movements. Biochemical analyses indicate that RPT2 is purified in the crude microsomal fraction, as well as phot1 and NPH3, and that RPT2 makes a complex with phot1 in vivo. On the other hand, NPH3 is not necessary for stomatal opening or chloroplast relocation. Thus, these results suggest that phot1 and phot2 choose different signal transducers to induce three responses: phototropic response of hypocotyl, stomatal opening, and chloroplast relocation.
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Inada
authors.forename: Maki
authors.initials: M
authors.lastname: Ohgishi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Mayama
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Okada
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakai
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism; D056931:Cryptochromes; D018744:DNA, Plant / Q000235:genetics; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D017343:Genes, Plant; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D017956:Photoreceptor Cells, Invertebrate; D018524:Phototropism / Q000502:physiology; D030821:Plants, Genetically Modified; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D018744:DNA, Plant; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D046911:Macromolecular Substances; C400222:NPH3 protein, Arabidopsis; C405209:RPT2 protein, Arabidopsis; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; C119828:cry protein, Drosophila