采用TD PCR(Touch down PCR)法从水母雪莲(Saussurea medusa Maxim)红色系愈伤组织cDNA文库中筛选并克隆了雪莲Myb转录调控因子SmP (S.medusa Maxim Myb related P gene)基因。序列分析表明该基因全长969bp,包括一个771bp的完整开放阅读框架(ORF),编码一个256氨基酸残基的蛋白质。氨基酸序列的同源性分析表明在N-端具有两个典型的R2R3-Myb-DNA结合结构域。C-端富含亲水的丝氨酸S(18.38%),且以寡聚体的形式存在,具有转录调控因子激活结构域常见的特征。
A full length cDNA encoding a MYB related regulatory gene was isolated from a cDNA library prepared from mRNAs of the red line callus of S. medusa by TD PCR. The cDNA, designated SmP, is 969 nucleotides long and has an open reading frame of 771 bp with a deduced amino acid sequence of 256 residues.The putative protein of SmP has two typical conversed R2R3 Myb DNA binding domains in N terminal and displays a rather high degree of similarity to OsMYB from rice and LBM1 from tobacco, showing 73% and 70% identity within the DNA binding domains. However, the C terminal domain of the SmP protein does not show obvious similarity to any other known protein sequence. It is rich in hydrophilic amino acids, especially in serine residues (18 38%), partly organized in homopolymeric stretches, a feature often found in activation domain of transcription factors.