Feldman R A, Hanafusa T, Hanafusa H
Cell. 1980 Dec;22(3):757-65. doi: 10.1016/0092-8674(80)90552-8.
Fujinami sarcoma virus (FSV), a newly characterized avian sarcoma virus, produces a protein of 140,000 daltons (p140) in infected cells. p140 is the product of a fused gene consisting of a part of the gag gene of avian retrovirus and FSV-unique sequences which are not related to the src sequences of Rous sarcoma virus. In vivo, p140 was found to be phosphorylated at both serine and tyrosine residues. Immunoprecipitates of p140 with antiserum against gag gene-coded proteins had a cyclic nucleotide-independent protein kinase activity which phosphorylated p140 itself, rabbit IgG of the immune complex and alpha-casein, an externally added soluble protein substrate. The phosphorylation was specific to tyrosine of the substrate proteins. p140 was phosphorylated in vitro at the same two tyrosine residues that were phosphorylated in vivo. The phosphate transferred to tyrosine residues of p140 forms a stable bond: it does not turn over during the kinase reaction, and the 32P-phosphate of p140 labeled in vitro or in vivo is not transferred to alpha-casein. FSV-p140 differs from p60src, the transforming protein of Rous sarcoma virus, in its marked preference of Mn2+ to Mg2+ ions, and in its inability to use GTP instead of ATP as the donor of gamma-phosphate.
藤浪肉瘤病毒（FSV）是一种新鉴定出的禽肉瘤病毒，在受感染细胞中产生一种140,000道尔顿的蛋白质（p140）。p140是一个融合基因的产物，该融合基因由禽逆转录病毒的gag基因的一部分和与劳氏肉瘤病毒的src序列无关的FSV独特序列组成。在体内，发现p140在丝氨酸和酪氨酸残基上均被磷酸化。用针对gag基因编码蛋白的抗血清对p140进行免疫沉淀，具有一种不依赖环核苷酸的蛋白激酶活性，该活性可使p140自身、免疫复合物的兔IgG以及外部添加的可溶性蛋白底物α-酪蛋白磷酸化。这种磷酸化作用对底物蛋白的酪氨酸具有特异性。p140在体外被磷酸化的两个酪氨酸残基与在体内被磷酸化的相同。转移到p140酪氨酸残基上的磷酸形成稳定的键：在激酶反应过程中不会周转，并且体外或体内标记的p140的32P-磷酸不会转移到α-酪蛋白上。FSV-p140与劳氏肉瘤病毒的转化蛋白p60src不同，它明显更倾向于Mn2+而非Mg2+离子，并且不能使用GTP替代ATP作为γ-磷酸的供体。
