Brown R E, Stephenson F A, Markello T, Barenholz Y, Thompson T E
Chem Phys Lipids. 1985 Aug 30;38(1-2):79-93. doi: 10.1016/0009-3084(85)90059-3.
A transfer protein specific for glycolipids has been isolated from bovine brain. As judged by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, the protein is 68% pure and has a molecular weight of 20 000. Three different assays were employed to study the protein's specificity and glycolipid binding properties. The protein transferred several different neutral glycosphingolipids and ganglioside GM1 equally well, but failed to accelerate phosphatidylcholine or sphingomyelin intervesicular movement. The protein's ability to interact with glycolipids was strongly influenced by the physical properties of the matrix phospholipid in which the glycolipids reside. Both the phase state of the phospholipid matrix and bilayer curvature affected glycolipid intervesicular transfer rates. Protein binding to phospholipid vesicles containing either tritium-labeled or pyrene-labeled glucosylceramide could not be demonstrated by density gradient centrifugation or fluorescence energy transfer measurements, respectively. A specific association of the transfer protein for pyrene-labeled glucosylceramide was found when the fluorescence emission of the pyrene excimer-to-monomer ratio was measured suggesting that a portion of the fluorescent glycolipid was being sequestered from the phospholipid vesicles and was binding to the freely soluble protein.
一种对糖脂具有特异性的转运蛋白已从牛脑中分离出来。通过十二烷基硫酸钠（SDS）聚丙烯酰胺凝胶电泳判断，该蛋白纯度为68%，分子量为20000。采用了三种不同的测定方法来研究该蛋白的特异性和糖脂结合特性。该蛋白能同样有效地转运几种不同的中性糖鞘脂和神经节苷脂GM1，但不能加速磷脂酰胆碱或鞘磷脂的囊泡间移动。该蛋白与糖脂相互作用的能力受到糖脂所在基质磷脂物理性质的强烈影响。磷脂基质的相态和双层曲率均影响糖脂的囊泡间转移速率。分别通过密度梯度离心或荧光能量转移测量，均未证实该蛋白与含有氚标记或芘标记葡萄糖神经酰胺的磷脂囊泡结合。当测量芘激基缔合物与单体荧光发射比率时，发现该转运蛋白与芘标记的葡萄糖神经酰胺存在特异性结合，这表明一部分荧光糖脂从磷脂囊泡中被隔离出来并与可自由溶解的蛋白结合。
