The solution structures of epidermal growth factor and transforming growth factor alpha.

The structures of human epidermal growth factor (EGF) and human transforming growth factor alpha (TGF alpha) have been determined in solution using nuclear magnetic resonance techniques. The features of each structure are described and similarities and differences between them are discussed. The structures are combined with information from sequence homologies to produce a model of the receptor-recognition sites of EGF and TGF alpha, which can be tested in a site-directed mutagenesis programme. The model assists in explaining previous observations of sequence-activity relationships. The TGF alpha and EGF structures also serve as models for homologous modules in other extracellular proteins.