The consensus structure of the G-ribo motif. Helices 1 and 2, as well as connector regions, are arranged as in Figures 1A and 3. (Enclosed in rectangles) Base-pairs [0P;0Q] and [0R;0S] as well as nucleotide +1R, whose identities are very restricted in the known cases of the G-ribo motif. (In circles) The preferable identities for nucleotides +1P, +1S, and −1T. (X) An unrestrained nucleotide identity. The preferred length of the internal connector is 4 nt. (Dashed lines) The alternative possibilities for a G-ribo motif to form the third helix or not. The length of the region connecting positions 0S and 0P is calculated as the sum of the lengths of Connectors 1 and 2 plus 2 nt, if the third helix exists. The preferred length of this region is 5 nt.
