Philipp E I, Franke W W, Keenan T W, Stadler J, Jarasch E D
J Cell Biol. 1976 Jan;68(1):11-29. doi: 10.1083/jcb.68.1.11.
Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
从洋葱根尖和茎中分离出细胞核、核膜和粗面内质网（rER）。通过电子显微镜和生化方法测定各组分的结构保存情况和纯度。测定了总体组成数据（蛋白质、磷脂、非极性脂质、甾醇、RNA、DNA）、磷脂和脂肪酸模式、酶活性（ATP酶、ADP酶、IDP酶、葡萄糖-6-磷酸酶、5'-核苷酸酶、酸性磷酸酶以及NADH-和NADPH-细胞色素C还原酶）以及细胞色素含量。观察到一些DNA与核膜有稳定的、耐高盐的附着，以及一些RNA与经高盐处理的核膜和rER膜的结合。核膜和rER膜的磷脂模式相同，卵磷脂（约60%）和磷脂酰乙醇胺（20 - 24%）占主导。在分离过程中必须格外小心，以尽量减少磷脂酶对脂质的降解。非极性脂质，主要是甾醇和甘油三酯，占膜脂质的35 - 45%。两个膜组分中的甾醇含量都相对较高（甾醇与磷脂的摩尔比在0.12至0.43之间）。谷甾醇约占总甾醇的80%。棕榈酸、油酸和亚油酸是膜结合脂质以及储存脂质中最普遍的酸，在膜的磷脂、甘油三酯和游离脂肪酸中的比例相似。膜磷脂和甘油三酯中约80%的脂肪酸是不饱和的。在这些膜中鉴定出一种b5型细胞色素，但未检测到P - 450样细胞色素。在核膜和rER膜中都发现了NADH和NADPH - 细胞色素c还原酶，并且似乎在rER膜中含量更高。在磷酸酶中，Mg2 + - ATP酶以及程度较轻的ADP酶、IDP酶和酸性磷酸酶活性在各组分中存在，但大量的单价离子刺激的ATP酶、5'-核苷酸酶和葡萄糖-6-磷酸酶活性不存在。所获得的结果强调，动物细胞的rER和核膜之间所观察到的密切生化相似性延伸至植物细胞的这些组分。
