Krakow J S, Pastan I
Proc Natl Acad Sci U S A. 1973 Sep;70(9):2529-33. doi: 10.1073/pnas.70.9.2529.
The cAMP receptor requires cAMP for DNA binding at pH 8.0 but shows cAMP-independent DNA binding at pH 6.0. Incubation of the cAMP receptor with proteolytic enzymes in the presence of cAMP results in loss of DNA-binding ability at pH 8, while it is still able to bind cAMP and DNA at pH 6. Incubation with proteolytic enzyme in the absence of cAMP does not affect the DNA-binding properties of the cAMP receptor. After proteolysis in the presence of cAMP, analysis by sodium dodecyl sulfateacrylamide-gel electrophoresis shows that the 22,500-dalton subunit characteristic of the untreated protein has been completely replaced by a 12,500-dalton fragment.
环磷酸腺苷（cAMP）受体在pH 8.0时需要cAMP才能结合DNA，但在pH 6.0时表现出不依赖cAMP的DNA结合能力。在cAMP存在的情况下，用蛋白水解酶孵育cAMP受体，会导致其在pH 8时失去DNA结合能力，而在pH 6时仍能结合cAMP和DNA。在没有cAMP的情况下用蛋白水解酶孵育，不会影响cAMP受体的DNA结合特性。在cAMP存在下进行蛋白水解后，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析表明，未处理蛋白质特有的22,500道尔顿亚基已完全被一个12,500道尔顿的片段取代。
