Fig. 2.

Substrate specificity of the SARS-CoV ExoN. SARS-CoV nsp14-HC was incubated with different 5′-[³²P]-labeled substrates, and the reaction products were analyzed by denaturing PAGE and autoradiography. Lanes 1 and 2, 5′-[³²P]-labeled RNA markers with sizes indicated to the left; lanes 3 and 4, reactions with ssRNA3; lanes 5 and 6, reactions with a ribose-2′-O-methylated form of ssRNA3 (designated ssRNA9); lanes 7 and 8, reactions with ssDNA97; lanes 9 and 10, reactions with dsDNA97/98; lanes 11 and 12, reactions with ssRNAm1. Reactions were done in the presence (lanes 4, 6, 8, 10, and 12) or absence (lanes 3, 5, 7, 9, and 11) of nsp14-HC (ExoN).