Sagata N, Tsuzuku-Kawamura J, Nagayoshi-Aida M, Shimizu F, Imagawa K, Ikawa Y
Proc Natl Acad Sci U S A. 1985 Dec;82(23):7879-83. doi: 10.1073/pnas.82.23.7879.
Using a rabbit antiserum directed against a synthetic oligopeptide whose sequence was deduced from the nucleotide sequence of the XBL gene of bovine leukemia virus, we detected a 38-kDa protein in virus-producing cell lines. In vitro translation of hybrid-selected RNA unequivocally demonstrates that this protein, designated p38(XBL), is indeed encoded by the XBL gene. Unlike the other virus-encoded proteins, however, p38(XBL) resides within the cells without being incorporated into virions. It undergoes no gross post-translational modifications and has a relatively short half-life (5-6 hr) in vivo. Furthermore, cell fractionation combined with pulse-chase experiment reveals that a significant fraction (more than half) of the p38(XBL) localizes to the nucleus of the infected cell after synthesis. We conclude that the XBL gene of bovine leukemia virus is a functional gene encoding a nonvirion protein p38(XBL), which possibly functions within the nucleus of the infected cell to regulate viral or cellular gene expression. p38(XBL) is presumably translated from a doubly spliced, bicistronic mRNA that has the capability to encode another small polypeptide in a different reading frame.
利用一种针对合成寡肽的兔抗血清，该寡肽的序列是从牛白血病病毒XBL基因的核苷酸序列推导而来的，我们在产生病毒的细胞系中检测到一种38 kDa的蛋白质。对杂交选择的RNA进行体外翻译明确表明，这种名为p38(XBL)的蛋白质确实由XBL基因编码。然而，与其他病毒编码的蛋白质不同，p38(XBL)存在于细胞内，而不被整合到病毒粒子中。它没有明显的翻译后修饰，并且在体内具有相对较短的半衰期（5 - 6小时）。此外，细胞分级分离结合脉冲追踪实验表明，很大一部分（超过一半）的p38(XBL)在合成后定位于受感染细胞的细胞核中。我们得出结论，牛白血病病毒的XBL基因是一个功能性基因，编码一种非病毒粒子蛋白p38(XBL)，它可能在受感染细胞的细胞核内发挥作用，以调节病毒或细胞基因的表达。p38(XBL)大概是从一个双剪接的双顺反子mRNA翻译而来的，该mRNA有能力在不同的阅读框中编码另一种小多肽。
