Objective: To explore the correlation between structure domains and functions of chemokine receptor CXCR4. Methods: After the establishment of wild type chemokine.receptor CXCR4 and CXCR2 expressing cell lines, 5 CXCR4/CXCR2 chimeras, 2 CXCR4 mutants were stably expressed on CHO cell line. Binding activities of all variants with the ligand, recombinant human SDF-1β, signal transduction ability after stimulation and their function as coreceptor for HIV-1 were studied with ligand-binding assay, Cytosensor/ microphysiometry and cell-cell reporter gene fusion assay. Results: Among all 7 changed CXCR4 receptors, 3 chimeras (2444a, 4442, 4122), and 1 mutant (CXCR4-Tr) bond with SDF-1β in varying degrees, of which only 2444a totally and CXCR4-Tr partially maintain signaling. All changed receptors except for 4222 could act as coreceptors for HIV-1 (LAI) in varying degrees. Conclusion: Several structure domains of CXCR4 are involved in the binding with SDF-1β, among which, N-terminal extracellular domain has
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