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CD4+ lipid bilayers. A model for human immunodeficiency virus type 1 coat protein binding

M T Tosteson1, P F Tosi, C Nicolau

  • 1Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.

The Journal of Biological Chemistry
|June 25, 1991
PubMed

Insights

The human immunodeficiency virus type 1 (HIV-1) gp120 protein forms ion channels upon binding to CD4 receptors. This interaction is blocked by MHCII or OKT4A, suggesting a new method for detecting gp120.

Area of Science:

  • Virology
  • Immunology
  • Biophysics

Background:

  • The human immunodeficiency virus type 1 (HIV-1) coat glycoprotein, gp120, binds to the CD4 molecule on T-lymphocytes.
  • CD4 also serves as a receptor for major histocompatibility complex class II (MHCII).

Purpose of the Study:

  • To investigate the molecular events following the interaction between HIV-1 gp120 and CD4.
  • To develop a method for detecting gp120 using CD4-incorporated lipid bilayers.

Main Methods:

  • Incorporation of CD4 into lipid bilayers.
  • Recording electrical changes upon addition of gp120 to CD4-containing bilayers.
  • Assessing the effect of MHCII and OKT4A antibody pre-exposure on channel formation.

Main Results:

  • Interaction of gp120 with CD4-containing bilayers induced multistate ion-permeable channels.
  • Maximum channel conductance was measured at 380-400 picosiemens.
  • Pre-exposure of CD4+ bilayers to MHCII or OKT4A antibody prevented channel formation upon gp120 addition.

Conclusions:

  • CD4-containing bilayers bind gp120, MHCII, and OKT4A.
  • Binding of gp120 to CD4 induces the formation of ion-permeable channels.
  • CD4+ bilayers can be utilized as an assay for detecting gp120 in solution.

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