Van Damme J M, Smeets K, Torrekens S, Van Leuven F, Peumans W J
Laboratory for Phytopathology and Plant Protection, Catholic University of Leuven, Belgium.
Eur J Biochem. 1993 Oct 1;217(1):123-9. doi: 10.1111/j.1432-1033.1993.tb18226.x.
Lectin cDNA clones encoding the two mannose-binding lectins from ramsons (allium ursinum L.) bulbs, AUAI and AUAII (AUA, Allium ursinum agglutinin), were isolated and characterized. Sequence comparison of the different cDNA clones isolated revealed three types of lectin clones called LECAUAG0, LECAUAG1 and LECAUAG2, which besides the obvious differences in their sequences also differ from each other in the number of potential glycosylation sites within the C-terminal peptide of the lectin precursor. In vivo biosynthesis studies of the ramson lectins have shown that glycosylated lectin precursors occur in the organelle fraction of radioactively labeled ramson bulbs. Despite the similarities between the A. ursinum and the A. sativum (garlic) lectins at the protein level, molecular cloning of the two ramson lectins has shown that the lectin genes in A. ursinum are organized differently. Whereas in A. sativum the lectin polypeptides of the heterodimeric ASAI are encoded by one large precursor, those of the heterodimeric AUAI lectin are derived from two different precursors. These results are confirmed by Northern blot hybridization of A. ursinum RNA which, after hybridization with a labeled lectin cDNA, reveals only one band of 800 nucleotides in contrast to A. sativum RNA which yields two bands of 1400 and 800 nucleotides. Furthermore it is shown that the two mannose-binding lectins are differentially expressed.
从熊葱（Allium ursinum L.）鳞茎中编码两种甘露糖结合凝集素AUAI和AUAII（AUA，熊葱凝集素）的凝集素cDNA克隆被分离并进行了表征。对分离得到的不同cDNA克隆进行序列比较，发现了三种类型的凝集素克隆，分别称为LECAUAG0、LECAUAG1和LECAUAG2，它们除了序列上的明显差异外，凝集素前体C末端肽段内潜在糖基化位点的数量也各不相同。熊葱凝集素的体内生物合成研究表明，糖基化的凝集素前体出现在放射性标记的熊葱鳞茎的细胞器部分。尽管熊葱和大蒜（A. sativum）凝集素在蛋白质水平上有相似之处，但两种熊葱凝集素的分子克隆表明，熊葱中的凝集素基因组织方式不同。在大蒜中，异源二聚体ASAI的凝集素多肽由一个大的前体编码，而异源二聚体AUAI凝集素的多肽则来自两个不同的前体。用熊葱RNA进行的Northern印迹杂交证实了这些结果，与产生1400和800个核苷酸两条带的大蒜RNA相比，用标记的凝集素cDNA杂交后，熊葱RNA只显示出一条800个核苷酸的条带。此外，研究还表明这两种甘露糖结合凝集素的表达存在差异。
