Neurotrophins and their receptors: A convergence point for many signalling pathways

The neurotrophins are a family of proteins that are essential for the development of the vertebrate nervous system. Each neurotrophin can signal through two different types of cell surface receptor - the Trk receptor tyrosine kinases and the p75 neurotrophin receptor. Given the wide range of activities that are now associated with neurotrophins, it is probable that additional regulatory events and signalling systems are involved. Here, I review recent findings that neurotrophins, in addition to promoting survival and differentiation, exert various effects through surprising interactions with other receptors and ion channels.