Identification of the residues in human CD4 critical for the binding of HIV

J Arthos, KC Deen, MA Chaikin, JA Fornwald, G Sathe… - Cell, 1989 - cell.com
J Arthos, KC Deen, MA Chaikin, JA Fornwald, G Sathe, QJ Sattentau, PR Clapham
Cell, 1989cell.com
The CD4 molecule is a T cell surface glycoprotein that interacts with high affinity with the
envelope glycoprotein of the human immunodeficiency virus, HIV, thus serving as a cellular
receptor for this virus. To define the sites on CD4 essential for binding to gp120, we
produced several truncated, soluble derivatives of CD4 and a series of 26 substitution
mutants. Quantitative binding analyses with the truncated proteins demonstrate that the
determinants for high affinity binding lie solely with the first 106 amino acids of CD4 (the Vl …
Summary
The CD4 molecule is a T cell surface glycoprotein that interacts with high affinity with the envelope glycoprotein of the human immunodeficiency virus, HIV, thus serving as a cellular receptor for this virus. To define the sites on CD4 essential for binding to gp120, we produced several truncated, soluble derivatives of CD4 and a series of 26 substitution mutants. Quantitative binding analyses with the truncated proteins demonstrate that the determinants for high affinity binding lie solely with the first 106 amino acids of CD4 (the Vl domain), a region having significant sequence homology to immunoglobulin variable regions. Analysis of the substiUtion mutants further defines a discrete binding site within this domain that overlaps a region structurally homologous to the second complementarity-determining region of antibody variable domains. Finally, we demonstrate that the inhibition of virus in-* t Present address: Progenies Pharmaceuticals, Inc., Department of Molecular Immunology. Old Saw Mill Rover Road, Tarrytown, NY, 10591. fection and virus-mediated cell fusion by soluble CD4 proteins depends on their association with gp120 at this binding site.
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