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. Author manuscript; available in PMC: 2014 Sep 20.
Published in final edited form as: ACS Chem Biol. 2013 Jun 26;8(9):1955–1963. doi: 10.1021/cb400274z

Figure 1. CXCL121 and CXCL122 have discrete CXCR41–38 binding sites.

Figure 1

(A) The CXCL12 NMR structure (PDB ID 1SDF) solved in acetate (pH 4.9) was used to identify and model the I55C/L58C mutations for disulfide formation (yellow). Dimerization is inhibited when the helix is constrained to an acute angle relative to the β-sheet (33). Chemical shift perturbations (orange) produced by CXCR41–3 mapped onto (B) CXCL121 (PDB ID 1SDF) and (C) CXCL122 (PDB ID 2K01). Chemical shift perturbations unique to CXCL121 are highlighted in ruby. Both structures are rotated 180° relative to their respective ribbon representations. (D) CXCR41–38 induced chemical shift perturbations fitted to a quadratic binding equation resulted in CXCL121 and CXCL122 affinities of 3.5 ± 0.1 and 0.9 ± 0.3 µM, respectively.