Glycophorin A dimerization is driven by specific interactions between transmembrane α-helices

M. A. Lemmon, J. M. Flanagan, J. F. Hunt, B. D. Adair, B. J. Bormann, C. E. Dempsey, D. M. Engelman

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Abstract

Specific side-by-side interactions between transmembrane α-helices may be important in the assembly and function of integral membrane proteins. We describe a system for the genetic and biophysical analysis of these interactions. The transmembrane α-helical domain of interest is fused to the C-terminus of staphylococcal nuclease. The resulting chimera can be expressed at high levels in Escherichia coli and is readily purified. In our initial application we study the single transmembrane α-helix of human glycophorin A (GpA), thought to mediate the SDS-stable dimerization of this protein. The resulting chimera forms a dimer in SDS, which is disrupted upon addition of a peptide corresponding to the transmembrane domain of GpA. Deletion mutagenesis has been used to delineate the minimum transmembrane domain sufficient for this behavior. Site-specific mutagenesis shows that a methionine residue, previously implicated as a potential interfacial residue, can be replaced with other hydrophobic residues without disrupting dimerization. By contrast, rather conservative substitutions at a valine on a different face of the α-helix disrupt dimerization, suggesting a high degree of specificity in the helix-helix interactions. This approach allows the interface between interacting helices to be defined.

Original languageEnglish (US)
Pages (from-to)7683-7689
Number of pages7
JournalJournal of Biological Chemistry
Volume267
Issue number11
StatePublished - 1992

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Lemmon, M. A., Flanagan, J. M., Hunt, J. F., Adair, B. D., Bormann, B. J., Dempsey, C. E., & Engelman, D. M. (1992). Glycophorin A dimerization is driven by specific interactions between transmembrane α-helices. Journal of Biological Chemistry, 267(11), 7683-7689.