Figure 6. Functional effects of RP13-like mutations. (A) Effect of yPrp8^Jab1 mutations on the RNA-stimulated ATPase activity of yBrr2. Error bars represent standard errors of the mean of three independent experiments. yPrp8^ED/KK–yPrp8^{E2407K/D2410K} variant, designed based on the structure of hBrr2^HR–hPrp8^Jab1 to destabilize binding of the distal Prp8^Jab1 tail to the RNA-binding tunnel of Brr2, mimicking type III mutations. (B) Effect of yPrp8^Jab1 mutations on yBrr2's U4/U6 unwinding activity under conditions favoring RNA binding in vitro (200 nM yBrr2, 50 nM U4/U6, 30 °C). Error bars represent standard errors of the mean of at least two independent experiments. Except for the effects of type II variants of yPrp8^Jab1 (yPrp8^Jab1-R2388K and yPrp8^Jab1-F2392L), the data were reported in reference 42. ATP hydrolysis and U4/U6 unwinding were monitored as described.⁴²