Matten W T, Maness P F
Department of Biochemistry, University of North Carolina School of Medicine, Chapel Hill 27514.
Biochem J. 1987 Dec 15;248(3):691-6. doi: 10.1042/bj2480691.
A kinetic analysis of the tyrosine-specific protein kinase of pp60c-src from the C1300 mouse neuroblastoma cell line Neuro-2A and pp60c-src expressed in fibroblasts was carried out to determine the nature of the increased specific activity of the neuroblastoma enzyme. In immune-complex kinase assays with ATP-Mn2+ and the tyrosine-containing peptide angiotensin I as phosphoacceptor substrate, pp60c-src from the neuroblastoma cell line was characterized by a maximum velocity (Vmax.) that was 7-15-fold greater than the Vmax. of pp60c-src from fibroblasts. The neuroblastoma enzyme exhibited Km values for ATP (16 +/- 3 microM) and angiotensin I (6.8 +/- 2.6 mM) that were similar to Km values for ATP (25 +/- 3 microM) and angiotensin I (6.5 +/- 1.7 mM) of pp60c-src from fibroblasts. pp60v-src expressed in Rous-sarcoma-virus-transformed cells exhibited an ATP Km value (25 +/- 4 microM) and an angiotensin I Km value (6.6 +/- 0.5 mM) that approximated the values determined for pp60c-src in neuroblastoma cells and fibroblasts. These results indicate that the pp60c-src kinase from neuroblastoma cells has a higher turnover number than pp60c-src kinase from fibroblasts, and that the neural form of the enzyme would be expected to exhibit increased catalytic activity at the saturating concentrations of ATP that are found intracellularly.
对来自C1300小鼠神经母细胞瘤细胞系Neuro-2A的pp60c-src酪氨酸特异性蛋白激酶以及在成纤维细胞中表达的pp60c-src进行了动力学分析，以确定神经母细胞瘤酶比活性增加的性质。在用ATP-Mn2+和含酪氨酸的肽血管紧张素I作为磷酸受体底物的免疫复合物激酶测定中，神经母细胞瘤细胞系的pp60c-src的最大速度（Vmax.）比成纤维细胞的pp60c-src的Vmax.高7至15倍。神经母细胞瘤酶对ATP（16±3 microM）和血管紧张素I（6.8±2.6 mM）的Km值与成纤维细胞中pp60c-src对ATP（25±3 microM）和血管紧张素I（6.5±1.7 mM）的Km值相似。在劳氏肉瘤病毒转化细胞中表达的pp60v-src的ATP Km值（25±4 microM）和血管紧张素I Km值（6.6±0.5 mM）接近在神经母细胞瘤细胞和成纤维细胞中为pp60c-src测定的值。这些结果表明，神经母细胞瘤细胞中的pp60c-src激酶比成纤维细胞中的pp60c-src激酶具有更高的转换数，并且预计该酶的神经形式在细胞内发现的ATP饱和浓度下将表现出增加的催化活性。
