Simulation of re-differentiation of plants by transformation using a hormone-like peptide gene

从植物中分离的碱性7S球蛋白能够与动物胰岛素和胰岛素样生长因子结合，在蛋白质结构、蛋白激酶活性和亚细胞定位上与胰岛素受体相似，提示该蛋白具有胰岛素受体样功能。从豆类中分离的豆类胰岛素是一种4 kDa的多肽，可以与基本的7S球蛋白结合。豆类胰岛素和碱性7S球蛋白均定位于细胞壁和质膜。豆胰岛素对碱性7S球蛋白的磷酸化活性有刺激作用。添加豆类胰岛素可促进体外培养的胡萝卜组织的细胞增殖和分化。利用农杆菌转化系统将正义豆胰岛素基因导入胡萝卜和鸟脚三叶草的愈伤组织中，愈伤组织生长迅速，表面形成绿色斑点。因此，豆胰岛素是一种与动物胰岛素功能相关的激素样多肽。二硫键的几何构型在豆胰岛素和胰岛素之间是保守的。豆胰岛素的二硫键对磷酸化的刺激作用是不可缺少的。豆类胰岛素的二级和三级结构明显不同于胰岛素。然而，核磁共振分析表明，两个分子表面的氨基酸残基是相似的。这种相似性可以归因于它们对结合蛋白的特异结合活性和对蛋白质磷酸化的刺激作用。因此，在功能上，胰岛素样肽不仅存在于动物体内，还可能存在于高等植物中。

A basic 7S globulin isolated from plants is capable of binding to the animal insulin and insulin-like growth factors and shows similarity to the insulin receptor in protein structure, protein kinase activity and subcellular localization , suggesting this protein to have insulin receptor-like functions. A 4-kDa peptide, leginsulin isolated from legumes can bind to the basic 7S globulin. Both leginsulin and the basic 7S globulin are localized in the cell walls and plasma membranes. Leginsulin has stimulatory effect on phosphorylation activity of the basic 7S globulin. Cell proliferation and differentiation of in vitro cultured carrot tissues can be stimulated by adding leginsulin to the medium. The callus tissues of carrot and bird's-foot trefoil transfected the sense leginsulin gene using Agrobacterium transformation system showed rapid growth and formed green spots on the surface. It is concluded that leginsulin is a hormone-like peptide functionally related to animal insulins. The geometries of the disulfide bridges are conserved between leginsulin and insulin. The disulfide bridges of leginsulin are indispensable for stimulatory effect on the phosphorylation. Secondary and tertiary structures of leginsulin are apparently different from those of insulin. However, NMR analysis reveals the similarity in the amino acid residues on the surface of both molecules. The specific binding activity to their binding proteins and the stimulatory effect on protein phosphorylation can be attributed to this similarity. Thus, functionally insulin-like peptides are distributed in not only animals but possibly higher plants.