Photoactivated cross-linking of proteins within the erythrocyte membrane core.
We describe the reactions of three lipophilic, photoactivated cross-linking reagents, 1,5-diazidonapthalene, 4,4'-diazidobiphenyl, and the reversible 4,4'-dithiobisphenylazide, with erythrocyte membranes. Cross-linking occurs only upon photoactivation. At pH 7 to 8, only spectrin components are cross-linked by these reagents. At pH 5.0 to 5.5 several additional membrane proteins including the major "integral" membrane proteins are also cross-linked, despite equivalent binding of the cross-linkers at neutral and acid pH. The cross-linking rates of various membrane proteins at pH 5.0 to 5.5 depend distinctly upon duration of photoactivation. Bidimensional electrophoresis of membrane proteins after cross-linking with the reversible cross-linker, 4,4'-dithiobisphenylazide, has allowed for the identification of homopolymeric products of cross-linking (e.g. dimers and tetramers of Band 3) and heterocomplexes (spectrin plus other membrane proteins). The data suggest that at reduced pH, cross-linking can proceed not only at the membrane surface but also in the membrane core.
D001386:Azides; D001665:Binding Sites; D001713:Biphenyl Compounds; D004910:Erythrocyte Membrane / Q000648:ultrastructure*; D004912:Erythrocytes / Q000648:ultrastructure*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000097:blood* / Q000528:radiation effects; D008970:Molecular Weight; D009281:Naphthalenes; D011485:Protein Binding; D013049:Spectrin / Q000528:radiation effects
D001386:Azides; D001713:Biphenyl Compounds; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009281:Naphthalenes; D013049:Spectrin