Charged residues dominate a unique interlocking topography in the heterodimeric cytokine interleukin-12.
Yoon, C., Johnston, S.C., Tang, J., Stahl, M., Tobin, J.F., Somers, W.S.(2000) EMBO J 19: 3530-3541
- PubMed: 10899108 
- DOI: https://doi.org/10.1093/emboj/19.14.3530
- Primary Citation of Related Structures:  
1F42, 1F45 - PubMed Abstract: 
Human interleukin-12 (IL-12, p70) is an early pro-inflammatory cytokine, comprising two disulfide-linked subunits, p35 and p40. We solved the crystal structures of monomeric human p40 at 2.5 A and the human p70 complex at 2.8 A resolution, which reveals that IL-12 is similar to class 1 cytokine-receptor complexes. They also include the first description of an N-terminal immunoglobulin-like domain, found on the p40 subunit. Several charged residues from p35 and p40 intercalate to form a unique interlocking topography, shown by mutagenesis to be critical for p70 formation. A central arginine residue from p35 projects into a deep pocket on p40, which may be an ideal target for a small molecule antagonist of IL-12 formation.
Organizational Affiliation: 
Departments of Musculoskeletal Sciences and Biological Chemistry, Wyeth Research, 87 Cambridge Park Drive, Cambridge, MA 02140, USA.