Figure 1.

Deoxynucleotide sequences of the motif I and motif II truncates used in the binding and cross-linking experiments (see text). Invarient residues within each motif are shown in boldface type. The shift in the spacing of the 3′ conserved element between the motif I ligands is indicated by lines connecting the sequences. The proposed secondary structures of the motif II ligands are shown with base-pairing interactions denoted by lines connecting the nucleotides.