International
Tables for
Crystallography
Volume B
Reciprocal space
Edited by U. Shmueli

International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 387

Figure 2.5.7.6 

P. A. Penczekg
[Figure 2.5.7.6]
Figure 2.5.7.6

A high-resolution cryo-EM map allows backbone tracing. (a) Cryo-EM map of the cricket paralysis virus (CrPV) IRES RNA in complex with the yeast 80S ribosome determined at 7.3 Å resolution. The map is shown from the L1 protuberance side with the ribosomal 40S subunit in yellow, the 60S subunit in blue and the CrPV IRES in magenta. Landmarks for the 40S subunit: b, body; h, head; p, platform. Landmarks for the 60S subunit: CP, central protuberance; L1, L1 protuberance. PKIII denotes helix PKIII of the CrPV IRES RNA and SL the two stem loops present in the secondary structure of the RNA. (b) Structure of the CrPV IRES RNA. Based on the cryo-EM map and additional biochemical knowledge, the complete chain of the RNA is found (189 nucleotides could be traced). The IRES molecular model is shown as a coloured ribbon docked into the cryo-EM density (grey mesh). PK and P denote the individual helical elements of the IRES and SL denotes the stem loops (Schüler et al., 2006[link]).