Ghysdael J, Neil J C, Vogt P K
Proc Natl Acad Sci U S A. 1981 Apr;78(4):2611-5. doi: 10.1073/pnas.78.4.2611.
The gag-linked transformation-specific protein (polyprotein) p80 of Esh avian sarcoma virus (ESV) has been compared by tryptic peptide mapping with the homologous protein p90 of Yamaguchi 73 avian sarcoma virus (Y73). p80 of ESV and p90 of Y73 were found to share all four of their major nonstructural, transformation-specific, methionine-containing peptides and to have at least seven cysteine-containing transformation-specific peptides in common. Two nonstructural cysteine-containing peptides unique for ESV p80 and three specific for Y73 p90 were also identified. None of these peptides were found in the transforming gene product pp60src of Rous sarcoma virus (RSV) or in the transformation-specific polyproteins p105 of avian sarcoma virus PRCII (PRCII) or p140 of Fujinami sarcoma virus (FSV). ESV p80 and Y73 p90 are phosphorylated, and their tryptic phosphopeptides appear to be identical. In each polyprotein two major phosphopeptides were demonstrated, one containing phosphoserine, the other phosphotyrosine. The latter serves as phosphoacceptor for the protein kinase activities (ATP:protein phosphotransferase, EC 2.7.1.37) associated with p80 and p90. These protein kinase activities were found to be functionally indistinguishable but could be easily distinguished from the activities associated with PRCII p105 and FSV p140 on the basis of their cation requirement and target site specificity. On that basis also, p80/p90-associated protein kinases were found to be more similar to the enzymatic activity of pp60src than to those associated with the PRCII and FSV transformation-specific polyproteins. These results document a close genetic relationship between the two independently isolated sarcoma viruses Y73 and ESV. On the basis of the relatedness of transformation-specific proteins, ESV and Y73 constitute class III of avian sarcoma viruses, with class I containing the various strains of RSV and class II encompassing FSV and PRCII.
已通过胰蛋白酶肽图谱分析，将埃施氏禽肉瘤病毒（ESV）的与gag相关的转化特异性蛋白（多聚蛋白）p80，与山口73禽肉瘤病毒（Y73）的同源蛋白p90进行了比较。发现ESV的p80和Y73的p90共有其所有四个主要的非结构、转化特异性、含甲硫氨酸的肽段，并且至少有七个含半胱氨酸的转化特异性肽段相同。还鉴定出了两个ESV p80特有的非结构含半胱氨酸肽段和三个Y73 p90特有的肽段。在劳氏肉瘤病毒（RSV）的转化基因产物pp60src中，或在禽肉瘤病毒PRCII（PRCII）的转化特异性多聚蛋白p105或藤浪肉瘤病毒（FSV）的p140中，均未发现这些肽段。ESV p80和Y73 p90被磷酸化，并且它们的胰蛋白酶磷酸肽似乎相同。在每种多聚蛋白中都证实有两个主要的磷酸肽段，一个含磷酸丝氨酸，另一个含磷酸酪氨酸。后者作为与p80和p90相关的蛋白激酶活性（ATP：蛋白磷酸转移酶，EC 2.7.1.37）的磷酸受体。发现这些蛋白激酶活性在功能上无法区分，但根据其阳离子需求和靶位点特异性，可轻松与与PRCII p105和FSV p140相关的活性区分开来。基于此，还发现与p80/p90相关的蛋白激酶与pp60src的酶活性比与PRCII和FSV转化特异性多聚蛋白相关的酶活性更相似。这些结果证明了两种独立分离的肉瘤病毒Y73和ESV之间存在密切的遗传关系。基于转化特异性蛋白的相关性，ESV和Y73构成禽肉瘤病毒的III类，I类包含RSV的各种毒株，II类包括FSV和PRCII。
