RIA analysis of selected scFvs binding to GCN4(7P14P) peptide isolated by ribosome display and c11L34Ser mutant. RNA of single scFvs was translated in vitro in the presence of [35S]methionine, and translation mixtures containing 0, 1, 10, and 100 nM GCN4(7P14P) peptide were analyzed by RIA as described in Methods. Each bar represents the average of three samples. For experiments A and B, see Fig. 1.