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

Mark A. Lemmon, John M. Flanagan, John F. Hunt, Brian D. Adair, Barbara Jean Bormann, Christopher E. Dempsey, Donald M. Engelman

Research output: Contribution to journalArticlepeer-review

445 Scopus citations

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 - Apr 15 1992

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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