Electrophoretic mobility shift assays of LGP2 RD and mutants with dsRNA. (A) Retardation of 5′-Alexa Fluor 488-labeled dsRNA (25 bp, 60 nM) in a 10% native polyacrylamide gel after incubation with 400 nM wild-type (wt) LGP2 RD or indicated RD mutants, respectively. (B) Retardation of 5′-Alexa Fluor 488-labeled dsRNA (25 bp, 60 nM) in a 10% native polyacrylamide gel after incubation with increasing concentrations (0, 0.4, 0.8, 1.6, 3.2 and 6.4 µM) of wt LGP2 RD and mutants P606→K, W604→A and H576→Y. For the wild-type RD two distinct bands appear shifted compared to free dsRNA at low protein concentrations already. The mutants show unspecific shifting and lower affinity to the RNA, indicated by remaining free dsRNA bands for all protein concentrations.