FIGURE 4.
Primer extension inhibition (toeprint) analysis of 30S subunit binding to SDL cI-lacZ mRNA with a 5′-triphosphate (lanes 1–5), a 5′-monophosphate (lanes 6–10), or a 5′-hydroxyl (lanes 11–15). Lanes 1, 6, and 11 omit 30S subunits, and lanes 2, 7, and 12 omit tRNAfMet (1 μM when included). (Lanes 3,8,13) 30S subunit concentration (88 nM) is twofold higher than mRNA (44 nM) concentration. (Lanes 4,9,14) 30S subunit concentration (264 nM) is sixfold higher than mRNA concentration. (Lanes 2,5,7,10,12,15) 30S subunit concentration (528 nM) is 12-fold higher than mRNA concentration. The position of the toeprint signal is identified by an arrow.