Signal Transduction Proteins

 Signal Transduction Proteins Background

Signal transduction is the process by which an extracellular signaling molecule activates a membrane receptor that in turn alters intracellular molecules creating a response. Transmembrane receptors span the cell membrane, with part of the receptor outside and part inside the cell. The chemical signal binds to the outer portion of the receptor, changing its shape and conveying another signal inside the cell. Some chemical messengers, such as testosterone, can pass through the cell membrane, and bind directly to receptors in the cytoplasm or nucleus. Sometimes there is a cascade of signals within the cell. With each step of the cascade, the signal can be amplified, so a small signal can result in a large response.Eventually, the signal creates a change in the cell, either in the expression of the DNA in the nucleus or in the activity of enzymes in the cytoplasm.

Signal transduction is a group of basic and important processes in molecular cell biology to deliver a signal from outside the cell to inside and reduce a functional change within the cell. Signal transduction initiates with activation of a specific receptor located on the cell surface or inside the cell by extracellular signaling molecule. Then the active receptor leads a biochemical chain of events inside the cell to respond. Finally, changes about metabolism, shape, gene expression, or ability to divide are triggered depending on the cell type. During the delivery process, signal can be amplified at any step so that one signal molecule can reduce many responses.

Signal transduction systems help coordinate the activities of hundreds to trillions of cells in multicellular organisms. In multicellular organisms, there are a variety of mechanisms for cell-to-cell communication. For example, our skin grows at the right rate to replace loss of its surface every day of our lives. This accurate regulation exists in every tissue of our body, and once this fine regulation breaks down, cancer may occur. All these cannot realize without signal transduction.


Signal Transduction Networks

Many cells regulate their gene expressions by integrating multiple external signals. One of the principle challenges in life sciences is to understand how cells receive, process, and respond to information form the environment. These processes are generally controlled by the cellular signal transduction network. The signal transduction network is actually a cascade of biochemical reactions inside the cell that eventually modify the cellular activity, such as a transcription factor. A transcription factor is a protein that binds to the DNA and regulates the gene expression process. Since most of the cellular phenotypes are the result of gene expression, active control of the transcription factor activity has great importance in cell biology. However, our understanding in the signal transduction pathways is far from complete and a rational design of stimuli for regulating the networks is extremely difficult.


Signal Transduction reference

1. Shaw, Gerry. "Signal Transduction." Genetics. 2003. 17 Dec. 2015. 

2. Krauss G. Biochemistry of signal transduction and regulation[M]. John Wiley & Sons, 2006.