FIG. 6.

Comparison of endoribonuclease activities of the SARS-CoV Nsp15 and orthologs from other coronaviruses. (A) Activities of the IBV ortholog. An image of the cleavage products from R10.2 and R12 are shown. The proteins and RNA substrates used in each reaction mixture are indicated above the gel. The contents of all lanes were exposed to Nsp15, but an aliquot was removed and placed in the denaturing gel loading buffer within seconds of addition of the enzyme (<1 min). The sizes of the products (in nucleotides) are indicated to the left of the gel. Quantification of endoribonuclease activity, shown below the gel, refers to the percentage of the full-length RNA (% FL) remaining in each lane. (B) Activity of the MHV ortholog.