Components of Intracellular Signal Transduction

Components of Intracellular Signal Transduction Signaling Proteins 

The most important tools for intracellular signal transduction are the receptors, protein kinases, protein phosphatases, regulatory GTPases and adaptor proteins  

Receptors are the gates for incoming signals in that they specifically receive the signal and are thereby activated for further signal transduction. The main properties of receptors will be discussed below (see Section 3.4) 

A central tool for signal transmission in a cell is the 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 

The regulatory GTPases (see Chapter 5) function as switches that can exist in an active or inactive form. In the active form the GTPases can transmit signals to downstream components in the signaling chain. In the inactive form signal transmission in repressed. 

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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. 

One of the key components of mammalian signal transduction pathways is protein kinase C (PKC), which is activated by DAG and Ca (40) and phosphorylates serine and threonine residues. PKC contains a catalytic domain containing an ATP-binding site, and a regulatory domain where the sites involved in Ca, DAG and phospholipid binding reside. Whereas the inactive form of PKC is cytosolic, translocation to the plasma membrane is required for activity. This process is controlled by intracellular Ca concentrations. 

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-... 

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... 

The general features of ZP3 signal transduction can be summarized as follows intracellular Ca (Ca ) is elevated and promotes acrosome reactions. This pathway can then be divided into upstream components, which couple ZP3 signals to a Ca, response, and downstream effectors of Ca. . It is useful to focus on the central role of sperm Ca, in this process, given that this ion is necessary and sufficient for the initiation of acrosome reactions... 

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