期刊
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
卷 373, 期 1, 页码 211-217出版社
ACADEMIC PRESS INC
DOI: 10.1006/abbi.1999.1555
关键词
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Human CXCR4 was expressed in Sf9 insect cells using the Pac-to-Pac baculovirus expression system. The recombinant receptor exhibited ligand binding activities with a K-d value (3.3 nM) comparable to that of the native receptor. The role of four conserved cysteinyl residues was explored by site-directed mutagenesis. Each cysteine was individually changed to an alanine residue. All of the four mutants showed decreased ligand binding activity with increased K-d values although comparable levels of receptor expression were observed. These results suggest that each of these four cysteinyl residues may be important for the ligand binding of the receptor. Evidence suggests that the ionic interaction may be involved in ligand binding. Point mutation of several relatively conserved acidic residues (Asp-10, Asp-262, Glu-275, and Glu-277) to an alanine residue greatly decreased the ligand binding activity and affinity. Since SDF-1 alpha is a highly basic protein, these acidic residues may interact with the basic residues of SDF-1 alpha by ionic pairing in addition to other molecular interactions and play an important role in ligand binding. (C) 2000 Academic Press.
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