Cleavage specificities of human EndoG variants. (A)Sequence-specific cleavage assay. The structure of Eco R I-linearized pKJH20 DNA is shown at the top, with the open box designating the GC-rich sequence region (0.3 kb). Xba I site is located 1.6 kb from the Eco R I site at the 3' end of the linear pKJH20 DNA. In the cleavage assay, pKJH20 was cleaved by Eco R I and Xba I to generate the 2.8-kb and 1.6-kb substrates. Enzymes cleaving within the GC-rich sequence are expected to generate both the 2.8-kb and the 1.3-kb product fragments. (B) Electrophoresis analysis. The reaction mixtures containing 0.2 μg Eco R I/Xba I-treated pKJH20 and EndoG variants were incubated at 37°C for various periods. The resulting products were analyzed by 1.2% agarose gels. Arrowheads denote the substrate and product fragments.