Figure 4.
RNA-binding activity under oxidizing conditions of purified Rubisco is conserved throughout evolution. A, Purified Rubisco proteins from C. reinhardtii (C), spinach (S), tobacco (T), and R. rubrum (R) were used in UV cross-linking experiments performed in the presence or absence of GSSG. B, To determine the Kd of RNA binding, increasing concentrations of purified Rubisco proteins (10–500 nm) were UV cross-linked under oxidizing conditions to a random transcript (250 nts) that was transcribed from the multicloning site of pBluescript. Following RNase A treatment, the radiolabeled proteins were separated over 15% SDS-PAGE and their labeling was monitored using a phosphorimager. The relative amount of the bound radioactivity was plotted against the protein concentration using Kaleidograph software, and the Kd was calculated for each polypeptide.