MSU/ERDA Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1977 May;59(5):894-900. doi: 10.1104/pp.59.5.894.
The pathway of hydroxyproline-containing proteins to the cell wall, and to the growth medium in suspension-cultured Acer pseudoplatanus cells is traced by following the kinetics of the transfer of protein-bound (14)C-hydroxyproline into various fractions, and by comparing the hydroxyproline-arabinoside profiles of these fractions after alkaline hydrolysis.Hydroxyproline-rich protein passes directly from a membrane-bound compartment in the cytoplasm to the cell wall, not via an intermediate salt-soluble pool in the wall.There are at least three hydroxyproline-containing glycoproteins in the cell wall. One which possesses mono, tri, and tetraarabinoside side chains accounts for over 90% of the total hydroxyproline. This glycoprotein is "extensin."The hydroxyproline-containing proteins secreted into the medium have a glycosylation pattern markedly different from that of the major cell wall glycoprotein. It appears that there is little or no wall-like extensin in the medium.Approximately half of the protein-bound hydroxyproline secreted into the medium is linked to an arabinogalactan. This linkage is also found in a particulate wall protein precursor fraction from the cytoplasm, but only trace amounts can be detected in the cell wall.
追踪含羟脯氨酸蛋白进入细胞壁和悬浮培养的 Acer pseudoplatanus 细胞生长培养基的途径是通过跟踪蛋白结合的（14）C-羟脯氨酸转移到各个部分的动力学，并通过比较这些部分经碱性水解后的羟脯氨酸阿拉伯糖苷谱。富含羟脯氨酸的蛋白质直接从细胞质中膜结合的隔室进入细胞壁，而不是通过细胞壁中中间的盐溶性池。细胞壁中至少有三种含羟脯氨酸的糖蛋白。其中一种具有单、三、四阿拉伯糖苷侧链，占总羟脯氨酸的 90%以上。这种糖蛋白是“伸展蛋白”。分泌到培养基中的含羟脯氨酸蛋白的糖基化模式与主要细胞壁糖蛋白明显不同。似乎培养基中几乎没有或没有类似细胞壁的伸展蛋白。大约一半分泌到培养基中的蛋白结合羟脯氨酸与阿拉伯半乳糖连接。这种连接也存在于细胞质中的一种颗粒状壁蛋白前体部分，但在细胞壁中只能检测到痕量。
