Fig. 2.

Heterovalent RF-C11 inhibits the proteolysis of both Arg-nsP4 (R-nsP4) and Tyr-nsP4 (Y-nsP4) with higher efficacy than homovalent compounds or dipeptides. ^fDHFR^h-Ub^R48-X-nsP4^f (X = Arg or Tyr) was expressed in reticulocyte lysates, where its cotranslational cleavage yields the DHFR-Ub^R48 reference (DHFR; lower rows in each gel) and the X-nsP4 substrate (upper rows in each gel). The effects of synthesized compounds and dipeptides on degradation of Arg-nsP4 (A) and Tyr-nsP4 (B) were monitored in the presence of 150 μM bestatin by using time course anti-biotin Western blotting.