Harada J J, Spadoro-Tank J, Maxwell J C, Schnell D J, Etzler M E
Department of Botany, University of California, Davis 95616.
J Biol Chem. 1990 Mar 25;265(9):4997-5001.
Previous studies in our laboratory have shown that the Dolichos biflorus plant contains two similar lectins, a seed lectin and a stem and leaf lectin called DB58, that are present at different stages in the plant's life cycle. We have now established that each of these lectins is encoded by a separate gene by isolating these lectin genes from a library of D. biflorus nuclear DNA. Restriction mapping and nucleotide sequencing analyses show that the seed lectin and DB58 genes are located in the same transcriptional orientation within 3-kilobase pairs of one another. The lectin genes contain no introns and show greater than 90% nucleotide sequence identity in their protein coding and untranslated regions. This sequence similarity extends to both the 5' and 3' flanking regions of the genes; the major exception is that a 116-base pair segment located at position -215 to -100 from the transcription start site of the seed lectin gene is missing in the 5' flanking region of the DB58 gene. The possible significance of this segment with respect to the differential expression of these genes is discussed.
我们实验室之前的研究表明，双花扁豆植物含有两种相似的凝集素，一种种子凝集素和一种称为DB58的茎叶凝集素，它们存在于植物生命周期的不同阶段。我们现在已经确定，通过从双花扁豆核DNA文库中分离这些凝集素基因，每种凝集素都是由一个单独的基因编码的。限制性图谱和核苷酸测序分析表明，种子凝集素基因和DB58基因以相同的转录方向位于彼此3千碱基对范围内。凝集素基因不含内含子，在其蛋白质编码区和非翻译区显示出大于90%的核苷酸序列同一性。这种序列相似性延伸到基因的5'和3'侧翼区域；主要的例外是，位于种子凝集素基因转录起始位点-215至-100位置的一个116碱基对片段在DB58基因的5'侧翼区域缺失。讨论了该片段对于这些基因差异表达的可能意义。
