Altered membrane structure and surface potential in homozygous hemoglobin C erythrocytes

Fuyuki Tokumasu, Glenn A. Nardone, Graciela R. Ostera, Rick M. Fairhurst, Steven D. Beaudry, Eri Hayakawa, James A. Dvorak

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Hemoglobin C differs from normal hemoglobin A by a glutamate-to-lysine substitution at position 6 of beta globin and is oxidatively unstable. Compared to homozygous AA erythrocytes, homozygous CC erythrocytes contain higher levels of membrane-associated hemichromes and more extensively clustered band 3 proteins. These findings suggest that CC erythrocytes have a different membrane matrix than AA erythrocytes. Methodology and Findings: We found that AA and CC erythrocytes differ in their membrane lipid composition, and that a subset of CC erythrocytes expresses increased levels of externalized phosphatidylserine. Detergent membrane analyses for raft marker proteins indicated that CC erythrocyte membranes are more resistant to detergent solubilization. These data suggest that membrane raft organization is modified in CC erythrocytes. In addition, the average zeta potential (a measure of surface electrochemical potential) of CC erythrocytes was ≈2 mV lower than that of AA erythrocytes, indicating that substantial rearrangements occur in the membrane matrix of CC erythrocytes. We were able to recapitulate this low zeta potential phenotype in AA erythrocytes by treating them with NaNO2 to oxidize hemoglobin A molecules and increase levels of membrane-associated hemichromes. Conclusion: Our data support the possibility that increased hemichrome deposition and altered lipid composition induce molecular rearrangements in CC erythrocyte membranes, resulting in a unique membrane structure.

Original languageEnglish (US)
Article numbere5828
JournalPloS one
Volume4
Issue number6
DOIs
StatePublished - Jun 8 2009
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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