4-HELIX BUNDLE GROWTH-FACTORS AND THEIR RECEPTORS - PROTEIN-PROTEIN INTERACTIONS

Many growth factors and cytokines promote receptor clustering on bindi ng, At least three different protein-protein interaction sites are inv olved: cytokine-receptor I, cytokine-receptor II and receptor I-recept or II. Although structural data on these complexes are limited, recent structural and mutagenesis studies of the four-helix bundle class of cytokines are clarifying the nature of the complexes formed.