title: Molecular characterization of tobacco cDNAs encoding two small GTP-binding proteins.
abstract: We have isolated two cDNAs encoding small GTP-binding proteins from leaf cDNA libraries. These cDNAs encode distinct proteins which show considerable homology to members of the ras superfamily. Np-ypt3, a 1044 bp long Nicotiana plumbaginifolia cDNA, encodes a 24.4 kDa protein which shows 65% amino acid sequence similarity to the Schizosaccharomyces pombe ypt3 protein. The N-ypt3 gene is differentially expressed in mature flowering plants. Expression of this gene is weak in leaves, higher in stems and roots, but highest in petals, stigmas and stamens. Nt-rab5, a 712 bp long Nicotiana tabacum SR1 cDNA, encodes a 21.9 kDa protein which displays 65% amino acid sequence similarity to mammalian rab5 proteins. The expression pattern of the Nt-rab5 gene is very similar to that of the Np-ypt3 gene. The Nt-rab5 gene is virtually not expressed in leaves, higher in stems and roots, and highest in flowers. Both the Nt-rab5 and Np-ypt3 proteins were expressed in Escherichia coli and shown to bind GTP.
authors.affiliation: Friedrich-Miescher Institute, Basel, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Dallmann
authors.forename: L
authors.initials: L
authors.lastname: Sticher
authors.forename: C
authors.initials: C
authors.lastname: Marshallsay
authors.forename: F
authors.initials: F
authors.lastname: Nagy
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011905:Genes, ras / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010947:Plants, Toxic; D016133:Polymerase Chain Reaction; D029702:Schizosaccharomyces pombe Proteins; D014026:Nicotiana / Q000235:genetics*; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins
chemical_list: D005656:Fungal Proteins; D009838:Oligodeoxyribonucleotides; D010940:Plant Proteins; D029702:Schizosaccharomyces pombe Proteins; C075976:ypt3 protein, S pombe; C075978:rab5 protein, Nicotiana tabacum; C075977:YPT3 protein, Nicotiana plumbaginifolia; D006160:Guanosine Triphosphate; D004247:DNA; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins