Interactions between Lipid Monolayers and Band 3-Protein from Human Erythrocyte Membranes

Lipid monolayers at the air‐water interface were used as a model system to study the specificity of protein‐lipid interactions of band 3, the main integral protein (the anion transport protein) of human erythrocyte membranes. Band 3‐protein was isolated by zonal electrophoresis (in acetic acid/H2O/sucrose mixtures) of erythrocyte membranes preextracted in 10% acetic acid and solubilized in 92% acetic acid. Afterwards, the protein was transferred into aqueous solutions and injected into the aqueous subphase of monolayers of different lipid classes. The changes in monolayer surface pressure following protein addition were used as a measure of the strength of protein‐lipid interactions