Yasui K, Wakita T, Tsukiyama-Kohara K, Funahashi S I, Ichikawa M, Kajita T, Moradpour D, Wands J R, Kohara M
Department of Microbiology, The Tokyo Metropolitan Institute of Medical Science, Bunkyo-ku, Tokyo, Japan.
J Virol. 1998 Jul;72(7):6048-55. doi: 10.1128/JVI.72.7.6048-6055.1998.
The maturation and subcellular localization of hepatitis C virus (HCV) core protein were investigated with both a vaccinia virus expression system and CHO cell lines stably transformed with HCV cDNA. Two HCV core proteins, with molecular sizes of 21 kDa (p21) and 23 kDa (p23), were identified. The C-terminal end of p23 is amino acid 191 of the HCV polyprotein, and p21 is produced as a result of processing between amino acids 174 and 191. The subcellular localization of the HCV core protein was examined by confocal laser scanning microscopy. Although HCV core protein resided predominantly in the cytoplasm, it was also found in the nucleus and had the same molecular size as p21 in both locations, as determined by subcellular fractionation. The HCV core proteins had different immunoreactivities to a panel of monoclonal antibodies. Antibody 5E3 stained core protein in both the cytoplasm and the nucleus, C7-50 stained core protein only in the cytoplasm, and 499S stained core protein only in the nucleus. These results clearly indicate that the p23 form of HCV core protein is processed to p21 in the cytoplasm and that the core protein in the nucleus has a higher-order structure different from that of p21 in the cytoplasm. HCV core protein in sera of patients with HCV infection was analyzed in order to determine the molecular size of genuinely processed HCV core protein. HCV core protein in sera was found to have exactly the same molecular weight as the p21 protein. These results suggest that p21 core protein is a component of native viral particles.
利用痘苗病毒表达系统和用丙型肝炎病毒（HCV）cDNA稳定转化的CHO细胞系，对HCV核心蛋白的成熟和亚细胞定位进行了研究。鉴定出了两种分子大小分别为21 kDa（p21）和23 kDa（p23）的HCV核心蛋白。p23的C末端是HCV多聚蛋白的第191位氨基酸，p21是174位和191位氨基酸之间加工的产物。通过共聚焦激光扫描显微镜检查HCV核心蛋白的亚细胞定位。尽管HCV核心蛋白主要位于细胞质中，但也在细胞核中发现，并且通过亚细胞分级分离确定，在这两个位置其分子大小与p21相同。HCV核心蛋白对一组单克隆抗体具有不同的免疫反应性。抗体5E3在细胞质和细胞核中均能染色核心蛋白，C7-50仅在细胞质中能染色核心蛋白，499S仅在细胞核中能染色核心蛋白。这些结果清楚地表明，HCV核心蛋白的p23形式在细胞质中加工为p21，并且细胞核中的核心蛋白具有与细胞质中p21不同的高级结构。分析了HCV感染患者血清中的HCV核心蛋白，以确定真正加工的HCV核心蛋白的分子大小。发现血清中的HCV核心蛋白与p21蛋白的分子量完全相同。这些结果表明，p21核心蛋白是天然病毒颗粒的一个组成部分。
