Functional implications of interleukin-1 beta based on the three-dimensional structure.

The molecular structure of interleukin-1 beta, a hormone-like cytokine with roles in several disease processes, has been determined at 2.0 A resolution and refined to a crystallographic R-factor of 0.19. The framework of this molecule consists of 12 antiparallel beta-strands exhibiting pseudo-3-fold symmetry. Six of the strands make up a beta-barrel with polar residues concentrated at either end. Analysis of the three-dimensional structure, together with results from site-directed mutagenesis and biochemical and immunological studies, suggest that the core of the beta-barrel plays an important functional role. A large patch of charged residues on one end of the barrel is proposed as the binding surface with which IL-1 interacts with its receptor.