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PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
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Published on: July 27, 2017

Interaction of the lipid-associating domain of glycophorin with phospholipid bilayers

A Y Romans, J P Segrest

    Progress in Clinical and Biological Research
    |January 1, 1977
    PubMed

    Insights

    The lipid-associating domain (LAD) of human red cell membrane glycophorin forms torus-shaped structures within phospholipid bilayers. This association provides a model for studying boundary lipid phenomena in cell membranes.

    Area of Science:

    • Biochemistry
    • Membrane Biology
    • Biophysics

    Background:

    • Glycophorin, a human red cell membrane glycoprotein, spans the membrane with its N-terminus external and C-terminus cytoplasmic.
    • The 23-residue lipid-associating domain (LAD) of glycophorin exhibits unique hydrophobicity.
    • The LAD can be isolated as an aqueous insoluble tryptic peptide, T(is).

    Purpose of the Study:

    • To investigate the association of the isolated glycophorin LAD (T(is)) with phospholipid bilayers.
    • To characterize the structural and functional properties of T(is) within a lipid bilayer environment.
    • To correlate T(is)-lipid interactions with the natural state of glycophorin in red cell membranes.

    Main Methods:

    • Isolation of the T(is) peptide from glycophorin.
    • Formation of T(is):phospholipid vesicles.
    • Freeze fracture electron microscopy to study T(is) structure.
    • Pyrene fluorescence spectroscopy, differential scanning calorimetry, and ionic permeability assays to assess T(is)-lipid interactions.

    Main Results:

    • T(is) spontaneously associates with phospholipid bilayers under specific conditions.
    • Freeze fracture studies reveal T(is) forms multimeric, torus-shaped intramembranous structures (80 Å diameter, n>4).
    • A critical multimer concentration (CMC) for T(is) in lipid bilayers was identified.
    • Physico-chemical techniques indicate the T(is):phospholipid system is suitable for studying boundary lipid phenomena.

    Conclusions:

    • The isolated glycophorin LAD (T(is)) self-assembles into defined structures within lipid bilayers.
    • This model system allows for detailed investigation of protein-lipid boundary interactions.
    • Findings provide insights into the behavior of glycophorin within the native red cell membrane.

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