Ligand Binding Characteristics of CXCR4 Incorporated into Paramagnetic Proteoliposomes
| Autor: | Tajib Mirzabekov, Woj M. Wojtowicz, Gregory J. Babcock, Joseph Sodroski |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Receptors
CXCR4 Receptors CCR5 Protein Conformation Proteolipids viruses Cell Separation Thymus Gland HIV Envelope Protein gp120 Ligands Transfection Binding Competitive Biochemistry Epitope Cell Line Chemokine receptor Dogs Animals Humans Receptor Molecular Biology Cells Cultured chemistry.chemical_classification CXCR4 antagonist Dose-Response Relationship Drug Ligand binding assay Temperature virus diseases Cooperative binding Cell Biology Flow Cytometry Lipid Metabolism Ligand (biochemistry) Precipitin Tests Kinetics Spectrometry Fluorescence chemistry CD4 Antigens Glycoprotein Protein Binding |
| Zdroj: | Journal of Biological Chemistry. 276:38433-38440 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m106229200 |
| Popis: | The G protein-coupled receptor CXCR4 is a coreceptor, along with CD4, for the human immunodeficiency virus type 1 (HIV-1) and has been implicated in breast cancer metastasis. We studied the binding of the HIV-1 gp120 envelope glycoprotein (gp) to CXCR4 but found that the gp120s from CXCR4-using HIV-1 strains bound nonspecifically to several cell lines lacking human CXCR4 expression. Therefore, we constructed paramagnetic proteoliposomes (CXCR4-PMPLs) containing pure, native CXCR4. CXCR4-PMPLs specifically bound the natural ligand, SDF-1α, and the gp120s from CXCR4-using HIV-1 strains. Conformation-dependent anti-CXCR4 antibodies and the CXCR4 antagonist AMD3100 blocked HIV-1 gp120 binding to CXCR4-PMPLs. The gp120-CXCR4 interaction was blocked by anti-gp120 antibodies directed against the third variable (V3) loop and CD4-induced epitopes, structures that have also been implicated in the binding of gp120 to the other HIV-1 coreceptor, CCR5. Compared with the binding of R5 HIV-1 gp120s to CCR5, the gp120-CXCR4 interaction exhibited a lower affinity (K d = 200 nm) and was dependent upon prior CD4 binding, even at low temperature. Thus, although similar regions of X4 and R5 HIV-1 gp120s appear to be involved in binding CXCR4 and CCR5, respectively, differences exist in nonspecific binding to cell surfaces, affinity for the chemokine receptor, and CD4 dependence at low temperature. |
| Databáze: | OpenAIRE |
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