Fig. 2.

MN9D and PC12 cytoplasmic proteins bind specifically to sequences between the KpnI and ApaI sites of TH mRNA 3′-UTR. Cytoplasmic proteins were isolated from MN9D and PC12 cells and incubated with radiolabeled RNA encoding TH mRNA 3′-UTR sequences between the KpnI and SphI sites as noted in the diagram. The black region between 1552 and 1578 designates the polypyrimidine-rich domain. Competitor RNAs were added to the incubation mixtures 15 min before the radiolabeled probe at 100-fold molar excess concentrations. The arrow designates the specifically bound RNA-protein complex.