Yu X M
Shanghai Institute of Biochemistry, Academia Sinica, People's Republic of China.
Virology. 1991 Mar;181(1):386-9. doi: 10.1016/0042-6822(91)90510-i.
A large surface protein of human hepatitis B virus was expressed from a mutated S gene in which both the reported retention sequence (aa 2-19) and the C-terminal half of the preS1 region (aa 66-117) were deleted. This retention sequence-free protein was not secreted from the monkey kidney cell line COS-M6 in transient expression assays. When this large S protein was overexpressed in the presence of the major S protein, the secretion of the latter was severely inhibited. Moreover, the presence of S protein in large abundance did not facilitate the secretion of the mutated large S protein at all, indicating that it was subject to more profound retention than the wild-type large S protein. The findings that, like the wild-type large S protein, this altered protein retained some of the properties of its C-terminal S domain, and that the preS1 region was still on its surface suggested that there was no extensive alteration of the polypeptide folding. The interpretation is favored that the C-terminal half of the preS1 region plays a crucial role in the secretion of the large S protein when its N-terminal retention sequence is not present.
从一个突变的S基因表达出了乙型肝炎病毒的一种大表面蛋白，在该突变S基因中，报告的保留序列（氨基酸2 - 19）和前S1区的C端一半（氨基酸66 - 117）均被删除。在瞬时表达试验中，这种无保留序列的蛋白未从猴肾细胞系COS - M6中分泌出来。当这种大S蛋白在主要S蛋白存在的情况下过表达时，后者的分泌受到严重抑制。此外，大量存在的S蛋白根本无助于突变大S蛋白的分泌，这表明它比野生型大S蛋白受到更严重的保留。这些发现表明，与野生型大S蛋白一样，这种改变的蛋白保留了其C端S结构域的一些特性，并且前S1区仍在其表面，这表明多肽折叠没有广泛改变。有人认为，当不存在N端保留序列时，前S1区的C端一半在大S蛋白的分泌中起关键作用，这种解释更受青睐。
