Kreisel W, Volk B A, Büchsel R, Reutter W
Proc Natl Acad Sci U S A. 1980 Apr;77(4):1828-31. doi: 10.1073/pnas.77.4.1828.
By using a four-step procedure (i, solubilization with Triton X-100; ii, affinity chromatography on concanavalin A-Sepharose; iii, affinity chromatography on wheat germ lectin-Sepharose; iv, preparative sodium dodecyl sulfate gel electrophoresis) a glycoprotein was isolated from rat liver plasma membrane. The molecular weight is 110,000 and the isoelectric point is 5.8. It contains L-fucose, N-acetylneuraminic acid, D-galactose, D-mannose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and considerable quantities of aspartate, threonine, serine, and leucine. In pulse-chase experiments the half-lives of methionine and arginine, representing the half-life of the protein, were determined as 70 hr and 78 hr, respectively. The half-lives of the terminal carbohydrates L-fucose and N-acetylneuraminic acid were 12.5 and 33 hr, respectively. The galactose half-life was 20 hr. From this it is concluded that terminal sugars turn over several times in the life-span of this protein molecule. This process may be operative during membrane recycling mechanisms.
通过使用四步程序（i，用Triton X-100溶解；ii，在伴刀豆球蛋白A-琼脂糖上进行亲和层析；iii，在麦胚凝集素-琼脂糖上进行亲和层析；iv，制备性十二烷基硫酸钠凝胶电泳），从大鼠肝细胞膜中分离出一种糖蛋白。其分子量为110,000，等电点为5.8。它含有L-岩藻糖、N-乙酰神经氨酸、D-半乳糖、D-甘露糖、N-乙酰-D-葡糖胺、N-乙酰-D-半乳糖胺，以及大量的天冬氨酸、苏氨酸、丝氨酸和亮氨酸。在脉冲追踪实验中，代表该蛋白质半衰期的甲硫氨酸和精氨酸的半衰期分别测定为70小时和78小时。末端碳水化合物L-岩藻糖和N-乙酰神经氨酸的半衰期分别为12.5小时和33小时。半乳糖的半衰期为20小时。由此得出结论，在该蛋白质分子的寿命期间，末端糖会周转数次。这个过程可能在膜循环机制中起作用。
