RNase probing of LSB RNA. (a)-(c) 3'-32P-labeled and (f)-(h) 5'-32P-labeled LSB RNA was treated with nucleases under different conditions: (a) and (f) 20°C, 5 min (minimizing self-cleavage); (b) and (g) 50°C, 60 min and self-cleavage product was analyzed either directly in the mixture or (c) and (h) after re-purifying by electrophoresis in denaturing polyacrylamide gel. Samples were analyzed as described for Figure 2 except that the concentration of V1 RNase was 1 × 10-3 units/μl. Spacer nucleotides C-4 and U-9 were numbered in 3'-5'-direction from cut site and marked with "-" sign. The results of experiments shown in Figure 3(a)-(c) and 3(f)-(h) and of others not shown are summarized on the proposed secondary structures for pre-cleaved (d) and post-cleaved LBS RNA (e). Symbols used are as in Figure 2.