Figure 1. RRM1 but not RRM2 is co-purified with endogenous RNA from E. coli lysates.

(A) Schematic representation of a TDP-43 domain structure. (B–D) RRM1 (solid curve) and RRM2 (broken curve) were overexpressed in E. coli BL21(DE3) and purified with Ni²⁺-affinity chromatography. (B) Crude lysates were loaded on the Ni²⁺-affinity resins, which were washed with a TN-low buffer. The bound proteins were eluted from the resins and examined spectroscopically. (C,D) Resins incubated with crude lysates were washed with a TN-high buffer, and the bound proteins were eluted. Fractions obtained in (C) the wash and (D) the elute steps were examined spectroscopically. (E) The fraction washed out by a TN-high buffer from the resins incubated with RRM1 crude lysates was treated with either DNase or RNase and analyzed with urea-PAGE.