Thomas A, Roth M J
Department of Biochemistry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854, USA.
Virology. 1995 Aug 1;211(1):285-9. doi: 10.1006/viro.1995.1402.
Earlier studies of murine leukemia viruses (MuLVs) have reported that a percentage of surface protein (SU) remains covalently associated with transmembrane protein (TM) through formation of disulfide bonds. Among MuLVs, there are three conserved cysteine residues within the extracellular domain of TM. These cysteine residues were substituted individually with serines to define their function and possible role in disulfide bonding with SU. Using oligonucleotide-directed mutagenesis, seven mutant constructs were generated with individual as well as multiple cysteine mutations. Transient transfection of all seven cysteine mutations resulted in nonviable virus. Analysis of intracellular proteins of producer mutant cell lines have demonstrated that precursor envelope protein (gPr80env; SU/TM) is being synthesized, but transport and processing of gPr80env is blocked in the endoplasmic reticulum. Two independent reversions of one cysteine mutation have been isolated and characterized.
早期对鼠白血病病毒（MuLVs）的研究报告称，一定比例的表面蛋白（SU）通过形成二硫键与跨膜蛋白（TM）保持共价结合。在MuLVs中，TM的细胞外结构域内有三个保守的半胱氨酸残基。这些半胱氨酸残基分别被丝氨酸取代，以确定它们在与SU形成二硫键中的功能和可能作用。利用寡核苷酸定向诱变，产生了七个具有单个以及多个半胱氨酸突变的突变体构建体。所有七个半胱氨酸突变体的瞬时转染均导致病毒无法存活。对产生突变的细胞系的细胞内蛋白质分析表明，前体包膜蛋白（gPr80env；SU/TM）正在合成，但gPr80env的运输和加工在内质网中被阻断。已分离并鉴定了一个半胱氨酸突变的两个独立回复突变体。
