Simon K, Lingappa V R, Ganem D
Department of Microbiology, University of California Medical Center, San Francisco 94143.
J Cell Biol. 1988 Dec;107(6 Pt 1):2163-8. doi: 10.1083/jcb.107.6.2163.
Hepatitis B surface antigen (HBsAg), the major coat protein of hepatitis B virus, is also independently secreted from infected cells as a lipoprotein particle. Secretion proceeds without signal sequence removal or cleavage of other segments of the polypeptide. We have examined the synthesis and transport of HBsAg in cultured cells expressing the cloned surface antigen gene. Our results show that HBsAg is initially synthesized as a integral membrane protein. This transmembrane form is slowly converted to a secreted lipoprotein complex in the lumen of the endoplasmic reticulum via a series of definable intermediates, after which it is secreted from the cell. This unusual export process shares many features with the assembly and budding reactions of conventional enveloped animal viruses. However, it differs importantly in its absence of a requirement for the participation of nucleocapsid or other viral proteins.
乙肝表面抗原（HBsAg）是乙肝病毒的主要外壳蛋白，它也作为脂蛋白颗粒从受感染细胞中独立分泌出来。分泌过程无需去除信号序列或切割多肽的其他片段。我们已经研究了在表达克隆表面抗原基因的培养细胞中HBsAg的合成和运输。我们的结果表明，HBsAg最初是作为一种整合膜蛋白合成的。这种跨膜形式通过一系列可定义的中间体在内质网腔中缓慢转化为分泌型脂蛋白复合物，然后从细胞中分泌出来。这种不同寻常的输出过程与传统包膜动物病毒的组装和出芽反应有许多共同特征。然而，它的一个重要区别在于不需要核衣壳或其他病毒蛋白的参与。
