title: Interactions of band 3-protein from human erythrocyte membranes with cholesterol and cholesterol analogues.
abstract: The interaction between cholesterol and band 3-protein from human erythrocyte membranes was studied by incorporating the solubilized protein into monolayers of cholesterol and related sterols at the air-water interface and measuring the changes in surface pressure which accompanied protein incorporation. The following results were obtained: 1) Band 3-protein shows a very strong interaction with cholesterol monolayers. Both apolar and polar bonds contribute to this interaction. 2) Steroids with a structure slightly different from that of cholesterol (especially with respect to the polar group and the side chain) in most cases show a reduced affinity for band 3-protein. Thus, the protein-sterol interaction is highly specific. It is assumed that the protein-cholesterol interaction can be subidivided into two parts: an unspecific one which results from contributions from several sterol molecules, and a specific one which is due to the high affinity binding of the protein and cholesterol. The structural element responsible for the high affinity interaction is assumed to be a sterol-binding niche on the surface of band 3-protein. The sterol is thought to be held in the niche by a hydrogen bond at its polar head and a variety of hydrophobic bonds along its ring system and side chain.
mesh_terms: D002784:Cholesterol / Q000031:analogs & derivatives*; D004910:Erythrocyte Membrane / Q000032:analysis*; D004912:Erythrocytes / Q000032:analysis*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D011312:Pressure; D011485:Protein Binding; D013261:Sterols; D013329:Structure-Activity Relationship; D013499:Surface Properties
chemical_list: D008565:Membrane Proteins; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D013261:Sterols; D002784:Cholesterol