Fig. 5. VgRBP71 binds directly to other localization elements. (A) The binding of VgRBP71 was measured in competition assays using internally radiolabeled VLE RNA (1 nM) in the presence of increasing concentrations of the designated unlabeled competitor RNA. Lane 1, VLE RNA alone; lane 2, VLE RNA with VgRBP71 and no competitor RNA; lanes 3, 7, 11 contain 5 nM competitor RNA; lanes 4, 8, 12 contain 10 nM competitor RNA; lanes 5, 9, 13 contain 25 nM competitor RNA; lanes 6, 10 and 14 contain 100 nM competitor RNA. (B) Autoradiographs of the mobility shift assays were scanned with a laser densitometer to quantitate the fraction of bound VLE RNA at each concentration of competitor RNA relative to that in the absence of competitor. The isotherms correspond to () VLE RNA, (•) An1 RNA, () VegT RNA, () Xcat-2RNA and () nonspecific RNA control. The data for VLE and nonspecific RNAs are taken from the assays presented in Fig. 2.