Institute of Low Temperature Science, Hokkaido University, Sapporo 060, Japan.
Plant Physiol. 1992 Apr;98(4):1248-54. doi: 10.1104/pp.98.4.1248.
The vacuolar membrane of radish (Raphanus sativus) taproot contained a large quantity of a protein of 23 kilodaltons that accounted for more than 25% of the total membrane proteins. The protein, tentatively named VM 23, was purified and characterized. VM 23 tends to aggregate at high temperature even in the presence of 1% sodium dodecyl sulfate. The apparent molecular size of VM 23 was estimated to be about 400 kilodaltons by polyacrylamide gel electrophoresis in the presence of 0.1% Triton X-100. VM 23 was partially extracted from the vacuolar membranes with chloroform:methanol, indicating its high hydrophobicity. The hydrophobic carboxyl modifier N,N'-dicyclohexylcarbodiimide bound covalently to VM 23. The results suggest that VM 23 may act as a secondary transport system coupled with the proton transport. The antibody against radish VM 23 reacted with the major proteins in the vacuolar membranes of mung bean (Vigna radiata) and castor bean (Ricinus communis) hypocotyls and pumpkin (Cucurbita moschata) epicotyl, but not with that of sugar beet (Beta vulgaris) taproot. VM 23 comigrated with vacuolar H(+)-pyrophosphatase on sucrose density gradient centrifugation after sonication of membranes, indicating that it is associated with the vacuolar membrane.
萝卜（Raphanus sativus）主根液泡膜含有大量 23 千道尔顿的蛋白质，占膜总蛋白的 25%以上。这种蛋白质暂定名为 VM 23，已被纯化并进行了特性鉴定。即使在 1%十二烷基硫酸钠存在的情况下，VM 23 在高温下也容易聚集。在 0.1% Triton X-100 存在下通过聚丙烯酰胺凝胶电泳，VM 23 的表观分子量估计约为 400 千道尔顿。VM 23 可部分用氯仿/甲醇从液泡膜中提取，表明其具有较高的疏水性。疏水性羧酸修饰剂 N,N'-二环己基碳二亚胺与 VM 23 共价结合。结果表明，VM 23 可能作为质子转运偶联的二级转运系统发挥作用。抗萝卜 VM 23 的抗体与绿豆（Vigna radiata）和蓖麻（Ricinus communis）下胚轴以及南瓜（Cucurbita moschata）上胚轴液泡膜中的主要蛋白质发生反应，但与甜菜（Beta vulgaris）主根中的蛋白质不发生反应。在对膜进行超声处理后，VM 23 在蔗糖密度梯度离心时与液泡膜 H(+)-焦磷酸酶共迁移，表明它与液泡膜相关。
