signal transduction or stimulus-response coupling

Molecular Mechanisms of Signal Transduction: "All living cells monitor their surrounding environments and elicit appropriate responses to changing conditions. Such stimulus-response coupling is essential for numerous and diverse processes such as growth and development, metabolic regulation, and sensing. Signal transduction pathways, through which information is passed sequentially from one protein component to the next, provide the molecular mechanism for linking input signals to output responses. Despite great diversity in the types of stimuli and responses involved in different pathways, a limited number of fundamental molecular strategies are used for signal transduction. One such strategy is reversible covalent modification, a process that regulates the activities of proteins. "