Casnellie J E, Harrison M L, Hellstrom K E, Krebs E G
J Biol Chem. 1983 Sep 10;258(17):10738-42.
The major in vitro substrate for a tyrosine protein kinase in the particular fraction of the lymphoma cell line LSTRA is a protein of approximately 58,000 daltons (pp58). In order to determine if this phosphorylation is unique to the LSTRA cells, the particulate fractions from normal mouse T lymphocytes and another lymphoma cell line, YAC-1, were examined for the presence of pp58 phosphorylation. These two cell types were found to contain this phosphorylation, although in vitro pp58 phosphorylation is elevated approximately 20-40-fold in the LSTRA cells over that found in T lymphocytes or YAC-1 cells. A comparison was also made of the levels of tyrosine protein kinase activity among these three cell types. Tyrosine protein kinase activity was measured in vitro using an exogenously added synthetic peptide substrate and in vivo by determining cellular phosphotyrosine levels. The results of these determinations indicate that the LSTRA cell line contains an elevated level of tyrosine protein kinase activity.
淋巴瘤细胞系LSTRA特定组分中酪氨酸蛋白激酶的主要体外底物是一种分子量约为58,000道尔顿的蛋白质（pp58）。为了确定这种磷酸化是否为LSTRA细胞所特有，对来自正常小鼠T淋巴细胞和另一种淋巴瘤细胞系YAC-1的颗粒组分进行了检测，以确定是否存在pp58磷酸化。发现这两种细胞类型都含有这种磷酸化，尽管在体外，LSTRA细胞中的pp58磷酸化水平比T淋巴细胞或YAC-1细胞中的高约20 - 40倍。还对这三种细胞类型中的酪氨酸蛋白激酶活性水平进行了比较。酪氨酸蛋白激酶活性在体外使用外源添加的合成肽底物进行测量，在体内通过测定细胞磷酸酪氨酸水平进行测量。这些测定结果表明，LSTRA细胞系中酪氨酸蛋白激酶活性水平升高。
