title: Preferential and asymmetrical accumulation of a Rac small GTPase mRNA in differentiating xylem cells of Zinnia elegans.
abstract: Rac-type small GTPases are known to function in some cellular processes in plants. To further understand the involvement of Rac type GTPases in plant development, we isolated from cultured Zinnia cells a gene (ZeRAC2) encoding a new Rac-type small GTPase. ZeRAC2 mRNA accumulates preferentially in xylogenic culture and transiently at the time when visible tracheary elements appear. Experiments with ZeRAC2 recombinant proteins demonstrated that ZeRAC2 binds to and hydrolyzes GTP. A GFP-ZeRAC2 fusion protein was localized to the plasma membrane. Together with the fact that ZeRAC2 possesses a putative geranylgeranylation site at the C-terminus, this suggests that ZeRAC2 acts on the plasma membrane. In situ hybridization indicated that ZeRAC2 mRNA accumulates preferentially in xylem parenchyma and tracheary element precursor cells, and surprisingly the accumulation is restricted to the site facing developing tracheary elements.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Nakanomyo
authors.forename: Benedikt
authors.initials: B
authors.lastname: Kost
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D000595:Amino Acid Sequence; D019659:Asteraceae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D049452:Green Fluorescent Proteins; D017403:In Situ Hybridization; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010802:Phylogeny; D018514:Plant Structures / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000097766:RAC2 GTP-Binding Protein
chemical_list: D018076:DNA, Complementary; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein