Cell signalling

Many different kinds of molecules transmit information between the cells of multicellular organisms. Although all these molecules act as ligands that bind to receptors expressed by their target cells, there is considerable variation in the structure and function of the different types of molecules that serve as signal transmitters. This section t discuss the major types of signaling molecules and the receptors with which they interact., and it   focuses on the mechanisms by which cell  receptors  function to regulate cell behavior.