Phosphorylated spectrins are likely constituents of major Ca2+ affinity sites.
Fixation with Ca2+ -glutaraldehyde of ghosts results in opaque membrane associated deposits similar to Ca2+ binding sites of native human erythrocytes. Following brief incubation in an ATP medium the number and size of major Ca2+ affinity sites is considerably enhanced. In addition to major Ca2+ affinity sites multiple minor sites are lining either aspect of the ghost membrane. Ghosts fixed with EDTA-glutaraldehyde are devoid of major Ca2+ affinity sites and they exhibit extreme low overall opacity. Ghosts previously partially despectrinated by incubation in 0.5 mM EDTA have lost major Ca2+ affinity sites, although minor binding sites appear unimpaired. The findings provide evidence of the demonstration of phosphorylated spectrins in major Ca2+ affinity sites.
D001665:Binding Sites / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000648:ultrastructure*; D004912:Erythrocytes / Q000648:ultrastructure*; D005404:Fixatives; D005976:Glutaral; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis*; D013049:Spectrin / Q000032:analysis* / Q000378:metabolism
D005404:Fixatives; D008565:Membrane Proteins; D013049:Spectrin; D004492:Edetic Acid; D002118:Calcium; D005976:Glutaral