The global conformation of junction IIIabc analyzed by comparative gel electrophoresis. We compare the electrophoretic mobility of the six species having two long arms (giving their names to the species) and two short arms, and analyze the data with the expectation that the mobility will depend on the angle subtended between the long arms (Duckett et al. 1988; Lilley 2000). In each case, we compare the mobilities of the six long-short species for the natural IRES junction (tracks 1–6) and its 4H derivative (tracks 7–12). The data have been interpreted in terms of the models indicated adjacent to the gels (left, IRES junction; right 4H junction). The analysis has been performed in the absence of added divalent ions (A) and in 1 mM Mg2+ (B).
