Figure 2.

Representation of amino acids in the membrane-binding region of PFO analyzed with the site saturation library.A, a ribosomal display was used to select and identify PFO variants against lipid vesicles with defined lipid composition. Figure adapted from (27) with permission. B, the structure of the tip of the D4 domain. Residues that were included in the analysis are highlighted. Labeling and coloring as in Figure 1B. C–E, enrichment of the SSL library at 17 randomized positions after selection against vesicles containing POPC (C), POPC vesicles containing 20 mol% Chol (D), and POPC vesicles containing 50 mol% Chol (E). The color scale represents log₂ of amino acid residue frequencies normalized to the input SSL library. The gray color represents amino acid residues that were not detected after selection. The red boxes outline amino acid residues present in the WT PFO. F, relative abundance of amino acid residues at the selected positions of 46 members of the CDC family, highlighting their variability. Red numbers mark residues used in the combinatorial library (see below).