Dickson C, Atterwill M
J Virol. 1980 Aug;35(2):349-61. doi: 10.1128/JVI.35.2.349-361.1980.
The polyprotein precursor to the envelope glycoproteins of mouse mammary tumor virus was investigated by using subcellular fractionation procedures, pactomycin mapping techniques, tunicamycin inhibition of glycosylation, and endo-beta-N-acetyl glucosaminidase H-catalyzed removal of glycosylated residues in order to characterize the biosynthesis and processing of the precursor. The results suggest that the precursor (Pr73env) is synthesized on the rough endoplasmic reticulum as a transmembrane protein, with the carboxyl terminus remaining on the cytoplasmic side. The apoprotein as an estimated molecular weight of 60,000 and acquires five core oligosaccharide units during synthesis. Cleavage of the precursor precedes the secondary glycosylation steps and therefore probably occurs before transport to the plasma membrane. However, a minor population of Pr73env containing complex oligosaccharides was also found in the plasma membrane. The order of the glycoproteins in the precursor, as determined by pactomycin mapping, in NH2-gp52-gp36-COOH.
利用亚细胞分级分离程序、放线菌酮定位技术、衣霉素对糖基化的抑制作用以及内切β-N-乙酰葡糖胺糖苷酶H催化去除糖基化残基等方法，对小鼠乳腺肿瘤病毒包膜糖蛋白的多蛋白前体进行了研究，以表征该前体的生物合成和加工过程。结果表明，前体（Pr73env）作为一种跨膜蛋白在糙面内质网上合成，其羧基末端留在细胞质一侧。脱辅基蛋白的估计分子量为60,000，在合成过程中获得五个核心寡糖单元。前体的切割先于二级糖基化步骤，因此可能发生在转运到质膜之前。然而，在质膜中也发现了一小部分含有复合寡糖的Pr73env。通过放线菌酮定位确定，前体中糖蛋白的顺序为NH2-gp52-gp36-COOH。
