Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma 73019.
Plant Physiol. 1980 Apr;65(4):648-57. doi: 10.1104/pp.65.4.648.
Pea cotyledons were injected with d-[(14)C]mannose or d-[(14)C]-glucosamine and incubated for 1 to 1.5 hours. Cotyledons were homogenized and subcellular fractions were isolated by differential centrifugation followed by linear sucrose density gradient centrifugation.Radioactivity that was precipitated by trichloroacetic acid was associated most extensively with rough endoplasmic reticulum, Golgi membranes, a membrane with a density of 1.14 grams per cubic centimeter (possibly plasma membrane) and an unidentified subcellular component with a density of 1.22 grams per cubic centimeter. Lower levels of incorporation were observed in protein bodies and mitochondria.Isolated membrane fractions were lipid-extracted to determine which components of the membrane contained the label. Rough endoplasmic reticulum contained the most extensively labeled lipids which had similar properties to the lipid intermediates thought to be involved in glycoprotein assembly. The lipid free residues of the various membrane fractions contained radioactivity that was released by protease treatment. Acid hydrolysis of the residues indicated that most of the radioactivity was associated with mannose or glucosamine. It appears that various subcellular components of the pea cotyledon possess glycoproteins that contain mannose and glucosamine.
豌豆子叶被注射了 d-[(14)C]甘露糖或 d-[(14)C]-葡萄糖胺，并孵育 1 至 1.5 小时。子叶被匀浆，并通过差速离心和线性蔗糖密度梯度离心分离出亚细胞部分。三氯乙酸沉淀的放射性与粗面内质网、高尔基体膜、密度为 1.14 克/立方厘米的膜（可能是质膜）和密度为 1.22 克/立方厘米的未鉴定亚细胞成分结合最紧密。在蛋白体和线粒体中观察到较低水平的掺入。分离的膜部分进行脂质提取，以确定膜的哪些成分含有标记物。粗面内质网含有标记最广泛的脂质，其性质与被认为参与糖蛋白组装的脂质中间产物相似。各种膜部分的无脂残基含有经蛋白酶处理释放的放射性。残基的酸水解表明，大部分放射性与甘露糖或葡萄糖胺有关。看来豌豆子叶的各种亚细胞成分都含有含有甘露糖和葡萄糖胺的糖蛋白。
