Reconstitution of intramembrane particles in recombinants of erythrocyte protein band 3 and lipid: effects of spectrin-actin association.
The integral membrane protein Band 3 of the human erythrocyte, either purified or in a crude Triton X-100 extract of ghosts, was combined with egg lecithin in a cholate solution. During dialysis to remove cholate, lipid bilayer vesicles formed in which Band 3 existed as a dimer and in which intramembrane particles indistinguishable from those in the native membrane were exposed by freeze-fracturing. The recombinant vesicles were stable in both high and low salt concentrations, sedimented at a density that increased in prportion to their protein content, and bound spectrin-actin extracted from erythrocyte ghosts. When spectrin-actin was associated with the vesicles, the behavior of the recombinant intramembrane particles simulated that of the erythrocyte ghost intramembrane particles: they were dispersed at pH 7.6 and aggregrated at pH 5-5.5. Thus, some of the characteristics of the native membrane have been reconstituted in the recombinant.
D000199:Actins / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000648:ultrastructure*; D004912:Erythrocytes / Q000648:ultrastructure*; D005614:Freeze Fracturing; D006801:Humans; D008081:Liposomes; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D010713:Phosphatidylcholines; D012995:Solubility; D013049:Spectrin / Q000378:metabolism*
D000199:Actins; D001798:Blood Proteins; D008081:Liposomes; D008563:Membrane Lipids; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D013049:Spectrin