Huber M T, Compton T
Program in Cellular and Molecular Biology and Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin 53706-1532, USA.
J Virol. 1998 Oct;72(10):8191-7. doi: 10.1128/JVI.72.10.8191-8197.1998.
The human cytomegalovirus (HCMV) gCIII envelope complex is composed of glycoprotein H (gH; gpUL75), glycoprotein L (gL; gpUL115), and a third, 125-kDa protein not related to gH or gL (M. T. Huber and T. Compton, J. Virol. 71:5391-5398, 1997; L. Li, J. A. Nelson, and W. J. Britt, J. Virol. 71:3090-3097, 1997). Glycosidase digestion analysis demonstrated that the 125-kDa protein was a glycoprotein containing ca. 60 kDa of N-linked oligosaccharides on a peptide backbone of 65 kDa or less. Based on these biochemical characteristics, two HCMV open reading frames, UL74 and TRL/IRL12, were identified as candidate genes for the 125-kDa glycoprotein. To identify the gene encoding the 125-kDa glycoprotein, we purified the gCIII complex, separated the components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and subjected gH and the 125-kDa glycoprotein to amino acid microsequence analysis. Microsequencing of an internal peptide derived from purified 125-kDa glycoprotein yielded the amino acid sequence LYVGPTK. A FASTA search revealed an exact match of this sequence to amino acids 188 to 195 of the predicted product of the candidate gene UL74, which we have designated glycoprotein O (gO). Anti-gO antibodies reacted in immunoblots with a protein species migrating at ca. 100 to 125 kDa in lysates of HCMV-infected cells and with 100- and 125-kDa protein species in purified virions. Anti-gO antibodies also immunoprecipitated the gCIII complex and recognized the 125-kDa glycoprotein component of the gCIII complex. Positional homologs of the UL74 gene were found in other betaherpesviruses, and comparisons of the predicted products of the UL74 homolog genes demonstrated a number of conserved biochemical features.
人巨细胞病毒（HCMV）gCIII包膜复合物由糖蛋白H（gH；gpUL75）、糖蛋白L（gL；gpUL115）以及第三种与gH或gL无关的125 kDa蛋白组成（M.T.休伯和T.康普顿，《病毒学杂志》71:5391 - 5398，1997；L.李、J.A.纳尔逊和W.J.布里特，《病毒学杂志》71:3090 - 3097，1997）。糖苷酶消化分析表明，该125 kDa蛋白是一种糖蛋白，在65 kDa或更小的肽主链上含有约60 kDa的N - 连接寡糖。基于这些生化特性，两个HCMV开放阅读框UL74和TRL/IRL12被鉴定为该125 kDa糖蛋白的候选基因。为了鉴定编码125 kDa糖蛋白的基因，我们纯化了gCIII复合物，通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳分离各组分，并对gH和125 kDa糖蛋白进行氨基酸微序列分析。对源自纯化的125 kDa糖蛋白的内部肽段进行微测序，得到氨基酸序列LYVGPTK。FASTA搜索显示该序列与候选基因UL74预测产物的第188至195位氨基酸完全匹配，我们将该基因命名为糖蛋白O（gO）。抗gO抗体在免疫印迹中与HCMV感染细胞裂解物中迁移约100至125 kDa的一种蛋白以及纯化病毒颗粒中的100 kDa和125 kDa蛋白发生反应。抗gO抗体还免疫沉淀了gCIII复合物，并识别gCIII复合物的125 kDa糖蛋白组分。在其他β疱疹病毒中发现了UL74基因的位置同源物，对UL74同源基因预测产物的比较显示了许多保守的生化特征。
