Polypeptide growth factors: Structure, function and mechanism of action

Abstract

Polypeptide growth factors are a diverse group of hormone-like agents that regulate growth and differentiation through cell surface receptors. They are generally represented by homologous families containing several members with distinct overlapping receptor interactions and hence, responsive tissue specificities. Similarly, their receptors are also clustered in family groups of sequence-related proteins. The neurotrophin group, characterized by its typical prototypical member nerve growth factor (NGF), has four members which interact variably with three receptors of the trk family. The activation of their tyrosine kinases initiates the characteristic responses. In PC12 cells, stimulation by NGF leads to activation of non-receptor tyrosine kinases and several phospholipid dependent pathways. The sum of these signals induce a variety of immediate early response genes that govern the phenotypic response. However, the minimum pathway (and its essential components) is not yet fully defined. © 1994 IUPAC