Characterization of the carrot beta-tubulin gene coding a divergent isotype, beta-2.
Four different beta-tubulin clones were isolated from carrot genomic and cDNA libraries. Their nucleotide sequences were determined 1 and their predicted amino acids were compared with each other. The predicted amino acid composition of the C-terminal region of three of them (beta-1, 3, 4) resembled one another, but that of one isotype (beta-2) was divergent. The beta-2 tubulin included two hydroxyl amino acids, serine and threonine, and consisted of a lower number of negatively charged amino acids than the others in the C-terminal region. The predicted hydrophobicity profile of the beta-2 tubulin around the residue 200 is less hydrophobic than beta-1, but it is still more hydrophobic than those of animal and fungal beta-tubulins. The beta-2 gene was transcribed in cultured cells and flowers, while the beta-1 gene was ubiquitously transcribed in cultured cells, roots, shoots and flowers. When the predicted amino acids of plant tubulin were compared with those of other organisms, substitutions from non-polar amino acids to those with hydroxyl group were conspicuous in the region corresponding to the third exon in the plant genes.
Okamura
S
S
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan. okamura@ms.toyama-mpu.ac.jp
Naito
K
K
Sonehara
S
S
Ohkawa
H
H
Kuramori
S
S
Tatsuta
M
M
Minamizono
M
M
Kataoka
T
T
D000595:Amino Acid Sequence; D000818:Animals; D010582:Bacteriophage lambda; D001483:Base Sequence; D002460:Cell Line; D018744:DNA, Plant; D018552:Daucus carota / Q000235:genetics*; D015870:Gene Expression; D017343:Genes, Plant; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000235:genetics*
D018744:DNA, Plant; D014404:Tubulin