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Signal Transduction in Cells

Amanda Robb, Elizabeth Friedl
  • Author
    Amanda Robb

    Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also certified in secondary special education, biology, and physics in Massachusetts.

  • Instructor
    Elizabeth Friedl

    Elizabeth, a Licensed Massage Therapist, has a Master's in Zoology from North Carolina State, one in GIS from Florida State University, and a Bachelor's in Biology from Eastern Michigan University. She has taught college level Physical Science and Biology.

Learn what signal transduction is and the roles of different relay proteins. Explore the signal transduction pathway and signal transduction cascades in cells. Updated: 02/01/2022

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What is Signal Transduction?

Signal transduction is a process where cells translate signals from the extracellular environment into changes inside the cell. The type of signals coming from the extracellular environment vary depending on the cell type and can include chemical signaling molecules from other cells, like hormones, from the cell itself, or changes in the environment, such as pressure, temperature, or light. All cells require signal transduction in order to sense their environment and respond appropriately. Cells in multicellular organisms, like humans, must have signal transduction pathways to coordinate their responses and help the organism maintain homeostasis.

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  • 0:08 What is Transduction?
  • 1:43 A Multi-Step Process
  • 3:03 The Components of Transduction
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Signal Transduction Response

Signal transduction allows cells to communicate through a three step process. The main three steps include:

  1. Reception
  2. Transduction
  3. Response

Reception is the first step and includes the process where the cell senses a signal in the environment. This is accomplished with proteins on the surface of the cell membrane called receptor proteins. These proteins detect changes, such as chemical signals from other cells, or changes to pressure, light or other sensations. Receptor proteins are transmembrane proteins, meaning they span the cell membrane and thus can detect changes on the extracellular side of the cell and transmit that signal to the inside of the cell. Some receptor proteins may cause a change in ion permeability, phosphorylation of other proteins, or a change in localization in the membrane. For example, growth factor receptors bind to growth hormones in the body and cause changes in the phosphorylation status of the receptor protein inside the cell. This triggers other protein activation in the next step, called transduction.

The next step in the signal transduction pathway is transduction. Here, the signal sensed by the receptor protein is transmitted to the inside of the cell. This may involve activating or deactivating other proteins. Transduction can activate a great number of molecules at once, causing a cascade of activation inside the cell. This helps the singular signal from outside the cell be translated quickly and efficiently into a change inside the cell.

Ultimately, the transduction leads to a response. A response is a change in cellular behavior due to the signal. The following are examples of what a response could include in a cell:

  • Changes in motility
  • Changes in cell shape and structure
  • Changes in gene expression
  • Changes in protein localization
  • Changes in cell growth or division
  • Initiation of programmed cell death


An example of a signal transduction pathway

signal transduction example


Thus, the three steps of signal transduction allow for quick and efficient changes in cellular behavior in response to a change in the environment.

Signal Transduction Pathway

Signal transduction depends on multi-step processes, called signal transduction pathways. During transduction, signals can be amplified by increasing the number of proteins being activated. This allows for a more widespread and quicker response.

Signal Transduction Cascade

The signal transduction pathway creates a cascade pattern of activation within the cell. The receptor protein activates other proteins that activate other proteins, forming an activation cascade that results in a change in cell behavior. Although the specific proteins activated are specific for each signal transduction pathway, there are some common activation strategies. For example, many of the proteins in the cascade are kinases. Kinases are proteins that add a phosphate group to another molecule, called phosphorylation. In signal transduction pathways, multiple proteins in the pathway can be kinases, creating an effect called a phosphorylation cascade. Other proteins can remove phosphate groups, called phosphatases. These proteins carry out the process of dephosphorylation which can turn off the signaling cascade.

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Frequently Asked Questions

What is the meaning of signal transduction?

The meaning of signal transduction is a process that cells use to sense changes in the environment and communicate with other cells. Signal transduction is both important for unicellular organisms to sense the environment and for multicellular organisms to communicate between cells.

What happens during signal transduction?

During signal transduction cells receive a signal from the external environment. This is translated into protein activation or deactivation in the cell, which ultimately results in a change in cellular behavior.

What are the steps in the signal transduction pathway?

There are three main steps in the signal transduction pathway:

  1. Reception - The cell senses a change in the environment
  2. Transduction - The signal is sent through the cell
  3. Response - There is a change in cellular behavior

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