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Structure of the integrin alphaIIb transmembrane segment

Tong-Lay Lau1, Varun Dua, Tobias S Ulmer

  • 1Department of Biochemistry and Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.

The Journal of Biological Chemistry
|April 18, 2008
PubMed

Insights

Integrin alpha and beta subunits transmit signals across cell membranes. The alphaIIb subunit

Area of Science:

  • Cell biology
  • Structural biology
  • Biochemistry

Background:

  • Integrins are crucial cell-adhesion receptors involved in bidirectional transmembrane signaling.
  • These receptors utilize single-pass transmembrane segments of alpha and beta subunits to mediate signaling.
  • Understanding the structural dynamics within the membrane is key to integrin function.

Purpose of the Study:

  • To elucidate the structural organization of the alphaIIb transmembrane segment.
  • To compare the structure of the alphaIIb transmembrane segment with that of the beta3 subunit.
  • To establish a structural basis for integrin transmembrane signaling.

Main Methods:

  • Analysis of the alphaIIb transmembrane segment structure using high-resolution techniques.
  • Sequence alignment of conserved residues across human integrin alpha subunits.
  • Comparative structural analysis with the beta3 transmembrane segment.

Main Results:

  • The alphaIIb transmembrane segment features a 24-residue alpha-helix followed by a backbone reversal.
  • This structural motif packs specific phenylalanine residues against the transmembrane helix.
  • Unlike the beta3 subunit, the alphaIIb helix length suggests minimal tilt, and the Gly-Phe-Phe motif is conserved across human alpha integrins.

Conclusions:

  • The alphaIIb transmembrane segment possesses a complex structure beyond a simple helix.
  • This unique structural motif is likely conserved across all integrin alpha subunits.
  • The findings provide a structural foundation for understanding integrin-mediated signaling and rearrangements upon subunit association.

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