Cooper C S, Quincey R V
Biochem J. 1979 Aug 1;181(2):301-8. doi: 10.1042/bj1810301.
The properties of RNA polymerase A, which lacked the subunits of 48 000, 37 000 and 16 000 mol. wt., were compared with those of RNA polymerase A by using native calf thymus DNA as the template. The results showed that: (1) the specific activity of RNA polymerase A was about one-third that of RNA polymerase A; (2) more than 80% of RNA polymerase A, but only about 25% of RNA polymerase A, made RNA; (3) initiation by RNA polymerase A, but not by RNA polymerase A, began after a lag of 2 min; (4) the temperature-dependence for productive binding to DNA was greater for RNA polymerase A; (5) the apparent Km for UTP was greater for RNA polymerase A. These results support the supposition that the subunits missing from RNA polymerase A are involved in DNA binding [Huet, Dezélée, Iborra, Buhler, Sentenac & Fromageot (1976) Biochimie 58, 71-80] and show also that the loss of these subunits affects the elongation reaction.
以天然小牛胸腺DNA为模板，将缺少分子量为48000、37000和16000亚基的RNA聚合酶A的特性与RNA聚合酶A的特性进行了比较。结果表明：（1）RNA聚合酶A的比活性约为RNA聚合酶A的三分之一；（2）超过80%的RNA聚合酶A能合成RNA，但RNA聚合酶A只有约25%能合成RNA；（3）RNA聚合酶A的起始反应在滞后2分钟后开始，而RNA聚合酶A则不然；（4）RNA聚合酶A与DNA有效结合的温度依赖性更大；（5）RNA聚合酶A对UTP的表观Km值更大。这些结果支持了这样的推测，即RNA聚合酶A中缺失的亚基参与DNA结合[于埃、德泽莱、伊博拉、比勒、森特纳克和弗罗马热奥（1976年）《生物化学》58，71 - 80]，并且还表明这些亚基的缺失影响延伸反应。
