Figure 3

RNase R interacts with the small ribosomal subunit. Cellular extracts were separated on sucrose gradients. Position of ribosomal subunits, ribosomes and polysomes along the gradient were monitored by UV 280 absorbance (UV280). Amount of RNase R in each fraction of the gradient was monitored using western blot. Amount of proteins along the gradient was monitored by Ponceau stain. (A) 10-30% sucrose gradient. Polysomes were separated from exponentially and cold shocked cells. (B) 5-20% sucrose gradients. Polysomes were separated from exponentially and cold shocked cells. Difference in subunits migration between the gradients is due to longer centrifugation time of cold shock sample. (C) 5-20% sucrose gradients. Polysome from cold shocked cells were separated, part of the sample was treated with EDTA which results in ribosomal subunits separation. The treatment changes pattern of RNase R in the gradient indicating its interaction with ribosomes.