Fine structure of the band 3 protein in human red cell membranes: Freeze-fracture studies

R. S. Weinstein, J. K. Khodadad, T. L. Steck

Research output: Contribution to journalArticlepeer-review


The major red cell membrane protein, band 3, is a glycoprotein which extends across the membrane from the extracellular space into the cytoplasmic compartment. It is widely held that band 3 is a component of the intramembrane particles (IMP) which can be demonstrated by freeze-fracture electron microscopy. In this study, we find that the outer surface poles of the IMP can be seen by freeze-etching after they are unmasked by proteolysis under conditions which excise the surrounding sialopeptides from the membrane. The poles appear as distinctive projections, 30-50 Å in diameter, the 'ES particles.' The ES particles remain associated with the outer surface of the membrane following cleavage of the band 3 polypeptide by chymotrypsin or pronase. This is consistent with previous biochemical studies which have shown that the 38,000-dalton outer surface segment of band 3 is intercalated in the lipid bilayer. A granulofibrillar component at the inner surface of the membrane is provisionally identified as the 40,000-dalton inner-surface domain of band 3.

Original languageEnglish (US)
Pages (from-to)47-57
Number of pages11
JournalProgress in clinical and biological research
VolumeNo 30
StatePublished - 1979

ASJC Scopus subject areas

  • Medicine(all)


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