Inhibition of fetal calf muscle nicotinic receptor binding to HIV-1 gp120 by the B2 synthetic peptide. (A) Increasing amounts (10, 100, and 300 μg/mL) of the synthetic peptide B2 were mixed with the diluted detergent-solubilized receptor (0.5 nmol of ¹²⁵I-α–bgt bound/L). Aliquots of each mixture were injected at a flow rate of 5 μL/min in a flow cell where gp120 had been previously covalently immobilized. Regeneration of the matrix was obtained by injection of 10 mmol/L NaOH at the end of each cycle. (B) Identical concentrations of a peptide (T18) of the same lenght, but with a random sequence, were injected in identical experimental conditions.