Effects of antisense oligonucleotides directed against the ψ-SL1 region on tight dimerization of Nef, Rev or Tat RNAs. (A) Representation of the ψ-SL1 region and antisense oligonucleotides used in this experiment. The two palindromic sequences with tight dimerization properties are boxed (28). asψ and asSL1 antisense oligonucleotides binding sites are represented by thick lines. (B) 1–561 wild-type (unspliced), Nef, Rev or Tat RNAs were incubated in dimer buffer at 55°C without or with a 20-fold molar excess of asψ, asSL1 or both oligonucleotides, and subjected to TBE electrophoresis. (C) Percentage dimerization for each RNA alone or with asψ, asSL1, or both oligonucleotides (represented by closed, stippled, hatched and open bars, respectively). The y-axis error bars represent the standard deviation of duplicate experiments.