The GDDG mutation does not destabilize the KH domain. Thermal stability of the GDDG mutants. 220-nm CD signal of wild-type (black) and mutant(s) (red) domains as a function of temperature (thin lines). The data are fitted using a two-state folded-to-unfolded model (thick line). The midpoint of the transition between the folded and unfolded state is indicated as a dashed line and reported in Supplementary Table S2 . Five of the six mutants show only negligible changes in stability. The sixth mutant (KH3 of ZBP1) shows a modest stabilization, with a ∼5°C shift in the measured T_m .