Figure 1.

(A) Structure of the SDF-1α dimer with the secondary structure assignments for monomer 1 based on the program insightii (Biosym Technologies, San Diego) shows the extended N-terminal loop proceeding into the single turn of a 3₁₀ helix and strands β1, β2, and β3 followed by the C-terminal helix packing almost orthogonally to the three-stranded antiparallel β-sheet. (B) The IL-8 dimer is shown to highlight the differences between the IL-8 and SDF-1α dimers.