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Helix-helix packing in a membrane-like environment
I Mingarro1, A Elofsson, G von Heijne
1Department of Biochemistry, Stockholm University, Stockholm, S-106 91, Sweden.
Journal of Molecular Biology
|October 31, 1997
Summary
Glycophorin A transmembrane helix dimerization is broader than previously thought. Mutants show tetramer formation, influenced by interface motif duplication.
Area of Science:
- Biochemistry
- Molecular Biology
- Membrane Protein Studies
Background:
- Glycophorin A transmembrane helix dimerization in SDS is a model for helix-helix packing.
- Previous studies suggested strict sequence specificity for this dimerization.
Purpose of the Study:
- To investigate the sequence specificity of glycophorin A transmembrane helix dimerization.
- To explore alternative oligomeric states like tetramers.
Main Methods:
- Insertion mutagenesis in the critical helix-helix interface segment of glycophorin A.
- Analysis of dimerization and tetramerization in a micellar environment (SDS).
Main Results:
- Efficient dimerization is mediated by a wider range of sequence motifs than previously reported.
- Mutants unable to dimerize can form significant amounts of tetramers.
- Duplication of the interface motif can induce specific tetramerization.
Conclusions:
- The sequence requirements for glycophorin A transmembrane helix dimerization are more flexible.
- Tetramer formation is a significant alternative oligomeric state, inducible by specific structural modifications.