Components of the Intracellular Signal Transduction

In the following we will deal with the basic components and principles of intracellular signal transduction and signal processing. The specific reactions and levels of signal transduction will be dealt with in detail in later chapters. 

Components of the intracellular signal transduction are proteins and small molecule messengers (fig. 3.3). An incoming signal is passed on from the receptor to down- 

The intracellular activation of enzymes in a signaling chain can lead to the formation of diffusible chemical signaling molecules in the cell. These intracellular signaling molecules are also termed second messengers. The second messenger molecules activate and recruit cognate enzymes for the further signal transduction. 

The most important components of intracellular signal transduction are the protein kinases, protein phosphatases, regulatory GTPases and adapter proteins  

A central tool for signal transmission in a cell is phosphorylation of proteins via protein kinases. Proteins can be reversibly activated or inactivated via phosphorylation. The phosphorylation status of a protein is controlled by the activity of both protein kinases and protein phosphatases (see chapter 7). Both classes of enzymes are elementary components of signaling pathways and their activity is subject to manifold regulation. 

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Components of the intracellular signal transduction systems include a family of proteins known as the G proteins, and low-molecular second messengers that are produced in response to the interaction of the... 

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