First let's see RBE, the Rev binding element: it is an RNA. The fragment shown here, 30 nucleotides in length, forms a hairpin structure.
This RNA fragment is part of the gene that codes for the envelope glycoprotein of the human immunodeficiency virus HIV-1.
spacefilling, or spheres, model.
Now let's how the Rev protein tightly associates with the structure of RBE (only a 17-amino acid peptide of Rev is shown).