Fig. 4.

Ribbon representation of the GM-linker structure. In S domain A, Ser-301 forms a hydrogen bond with the 2′-OH group of C221 in helix 8, and Leu-302, Ala-306, and Met-309 make hydrophobic interactions with Gly-67 and Leu-68 situated in the apical loop between αN3 and αN4 in the N domain. The NG domain is shown in blue, the RNA is shown in red, the M domain is shown in green, and the GM-linker is shown in orange. The GM-linker in S domain B is shown in gray. The side chain of Asp-311 in B is also shown. The overlay is based on the SRP54 M domains.