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Membrane Anchoring of α-Helical Proteins: Role of Tryptophan

The function of membrane proteins relies on a defined orientation of protein relative to lipid. In apparent correlation to protein anchoring, tryptophan residues are enriched in the lipid headgroup region. To characterize the thermodynamic and structural basis of this relationship in α-helical membrane proteins, we examined the role of three conserved tryptophans in the folding of the heterodimeric integrin αIIbβ3 transmembrane (TM) complex in phospholipid bicelles and mammalian membranes. In the homogenous lipid environment of bicelles, tryptophan was replaceable by residues of distinct polarities. The appropriate polarity was guided by the electrostatic potential of the tryptophan surrounding, suggesting that tryptophan can complement diverse environments by adjusting the orientation of its anisotropic side chain to achieve site-specific anchoring. As a sole membrane anchor, tryptophan made a contribution of 0.4 kcal/mol to TM complex stability in bicelles. In membranes, it proved more difficult to repl...

Authors:   Alan J. Situ; So-Min Kang; Benjamin B. Frey; Woojin An; Chungho Kim; Tobias S. Ulmer
Journal:   Journal of Physical Chemistry B
Year:   2018
DOI:   10.1021/acs.jpcb.7b11227
Publication date:   11-Jan-2018
Facts, background information, dossiers
  • stability
  • proteins
  • environment
More about American Chemical Society Publications
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