Figure 1.

Tertiary and quaternary structures of chemokines. Panel a shows the secondary structural ‘Greek Key' motif of chemokines, as typified by the obligate monomer CCL7/MCP-3. Three antiparallel β-pleated sheets overlay a C-terminal, α-helical domain. In panels b and c, dimers of the CXC chemokine CXCL8/IL-8 and CCL2/MCP-1 are shown. Note the elongation of the CCL2 dimer in comparison with the CXCL8 dimer. Panel d shows the CXCl4/PF-4 tetramer. The images were constructed using the program Pymol (http://www.pymol.org) using the respective pdb files (1BO0 1IL8, 1DOM and 1RHP) retrieved from the protein data Bank (http://www.rcsb.org/pdb).