Interaction of recombinant ankyrin-binding domain (ankBDn) and its mutants with PE/PC lipid monolayer.

A) Interaction of ankBDn and its mutants with PE/PC 3∶2 (w/w) monolayer. The first 38 amino acid residues of ankBDn are shown; substitutions are marked in red. The ankBDn plateau level is defined as 100% PE/PC binding activity and is equal to ∼2.5 mN/m. Plateau levels were obtained at a protein concentration of ∼25–35 nM. Higher plateau levels indicate increased penetration of the lipid monolayer by protein. Average values were calculated from at least three measurements. Significant differences from the plateau value obtained for wild-type ankBDn are marked (Student's t test): * p<0.05; ** p<0.0001. Details in “Materials and Methods”. B) Interaction of ankBDn and its quadruple mutant SSSA with PS/PC 3∶2 (w/w) monolayer. Interaction of ankBDn with PE/PC monolayer was defined as 100%.