Department of Agronomy, University of Kentucky, Lexington, Kentucky 40506.
Plant Physiol. 1970 Jun;45(6):663-6. doi: 10.1104/pp.45.6.663.
All membrane-containing fractions isolated from tobacco leaves contained free sterols, sterol glycosides, and sterol esters. The three sterol forms increased, on a dry weight basis, with a decrease in particle size. The supernatant fraction contained only trace amounts of sterol. The major sterols in all cellular fractions, in the order of decreasing amounts, were: stigmasterol, beta-sitosterol, campesterol, and cholesterol. The 500g pellet contained the largest percentage of free sterol, while the 46,000g pellet contained the largest percentage of esterified sterol. The individual sterol composition of the free sterol and sterol glycoside fraction was very similar; however, the composition of the sterol ester fraction varied widely among intracellular fraction. The intracellular distribution pattern of cholesterol-(14)C added to the isolation medium provided evidence that the intracellular sterol distribution pattern is not an artifact. These results support the suggestion that sterols in plant cells may have a physiological function associated with membranes.
从烟草叶片中分离得到的所有含膜级分均含有游离甾醇、甾醇糖苷和甾醇酯。这三种甾醇形式的含量随颗粒尺寸的减小而增加，在干重基础上增加。上清液级分仅含有痕量甾醇。所有细胞级分中的主要甾醇，按含量递减顺序为：豆甾醇、β-谷甾醇、菜油甾醇和胆固醇。500g 沉淀中游离甾醇的百分比最大，而 46000g 沉淀中酯化甾醇的百分比最大。游离甾醇和甾醇糖苷级分的单个甾醇组成非常相似；然而，甾醇酯级分的组成在细胞内级分之间差异很大。添加到分离介质中的胆固醇-（14）C 的细胞内分布模式提供了证据，表明细胞内甾醇分布模式不是人为的。这些结果支持了这样的观点，即植物细胞中的甾醇可能具有与膜相关的生理功能。
