Cells have evolved multiple strategies to adapt the composItIon and quality of their protein equipment to needs imposed by changing conditions within the organism. Extracellular stimuli that inform cells about such needs are hormones, cytokines and neurotransmitters, which bind to specific cell surface receptors. Inside the cell, secondary signals are then produced which, ultimately, initiate the expression of proteins giving novel functional properties to the stimulated cells. This process can be controlled at a transcriptional, posttranscriptional, translational or posttranslational level....

Cells have evolved multiple strategies to adapt the composition and quality of their protein equipment to needs imposed by changes in intra- and extracellular conditions. The appearance of pro teins transmit ting novel functional properties to cells can be controlled at a transcrip tional, posttranscriptional, translational or posttranslational level. Extensive research over the past 15 years has shown that transcriptional regulation is used as the predominant strategy to control the production of new proteins in response to extracellular stimuli. At the level of gene transcription, the...