Wojtaszek P, Bolwell G P
Division of Biochemistry, School of Biological Sciences, Royal Holloway and Bedford New College, University of London, Egham, Surrey, United Kingdom.
Plant Physiol. 1995 Jul;108(3):1001-12. doi: 10.1104/pp.108.3.1001.
Specific labeling of secondary cell walls of tracheary elements and of xylary and phloem fibers has been observed when wheat germ agglutinin (WGA) and anti-WGA antibodies were used during ultrastructural studies of French bean (Phaseolus vulgaris L.) hypocotyls. In this report we demonstrate that at least part of this labeling is due to the presence of secondary cell-wall-specific glycoproteins. Three major novel glycoproteins with relative molecular weights of 55,000, 86,000, and 90,000, purified by means of WGA-Sepharose affinity chromatography, have been characterized. Their amino acid composition indicates that they are not the members of known classes of structural cell-wall proteins, since they contain no hydroxyproline, a lower level of glycine than seen in glycine-rich proteins, and very little proline. N-terminal sequences of all three proteins show no significant homology with other proteins. Antibodies were raised against electrophoretically pure 90-kD glycoprotein. These were used to localize this protein in secondary cell walls of xylem tracheary elements and in xylary and phloem fibers, i.e. in the same compartments where labeling with WGA has been observed. To our knowledge this is one of the first biochemical and ultrastructural demonstrations of secondary cell-wall-specific glycoproteins.
在对菜豆（Phaseolus vulgaris L.）下胚轴进行超微结构研究时，使用小麦胚凝集素（WGA）和抗WGA抗体，观察到了管状分子次生细胞壁以及木质部和韧皮部纤维的特异性标记。在本报告中，我们证明这种标记至少部分归因于次生细胞壁特异性糖蛋白的存在。通过WGA-琼脂糖亲和层析纯化得到了三种主要的新型糖蛋白，其相对分子质量分别为55,000、86,000和90,000，并对其进行了表征。它们的氨基酸组成表明，它们不是已知结构细胞壁蛋白类别的成员，因为它们不含羟脯氨酸，甘氨酸含量低于富含甘氨酸的蛋白，脯氨酸含量也很少。这三种蛋白的N端序列与其他蛋白均无明显同源性。针对电泳纯的90-kD糖蛋白制备了抗体。这些抗体用于将该蛋白定位在木质部管状分子的次生细胞壁以及木质部和韧皮部纤维中，即在观察到WGA标记的相同区域。据我们所知，这是次生细胞壁特异性糖蛋白的首批生化和超微结构证明之一。
