Top and Middle: the secondary structures and envelopes of the domain constructs and the RRE, respectively, where domains II, III and IV are highlighted in magenta, domains I and V are highlighted in cyan, and the full-length RRE is in gray. Bottom: three views of superimposition of the envelopes. See also Figure S2, Table S1, and Movies S2 and S3, which shows all views of the fits.