The impact of molecular biology on understanding renal signal transduction

The information that cells require to grow and prosper comes from diverse sources, adjacent to them and from considerable distances. Through evolution, cells have developed multiple mechanisms to acquire and process information. When a signaling mechanism has been successful, it has been used repeatedly with relatively minor modifications, and consequently is seen throughout biology. Specificity comes from using precise combinations of signaling molecules to achieve different ends in different cell types. Among the signaling systems that fit this description include the receptor and nonreceptor tyrosine kinases, G protein-coupled receptors, cell attachment receptors, guanylate cyclases, ligand-gated ion channels, the second messenger dependent and independent protein kinases and phosphatases, and transcription factors. The consequence of this conservation of molecular mechanisms is that many basic regulatory systems, which cannot be dissected free of the complexity of mammals, can be understood in relatively simple, manipulable experimental systems. With information from simple systems and the tools of genetics and molecular biology, complex problems such as human physiology and disease may be understood and eventually controlled.