What are the Essential Parts of a Signaling Pathway

The signaling pathway is one that provides a signal for body function and physiology. The Essential Parts of a Signaling Pathway are

  1. Ligand
  2. Receptor
  3. Signal cascade
  4. ATP

A signal can lead to the growth, repair and even damage of the cells or tissue. These signal pathways occur at both the micro and macro levels.

At the macro level, it involves the direct action of hormones on the tissues or organs. At the micro-level, the action occurs at the cellular level.

But, both of them are essential for proper physiology. Any derangement in it would lead to disorders in the body.

Details on the Essential Parts of a Signaling Pathway

As said before, a signaling pathway mostly includes a ligand, receptor, ATP and also signal transmission cascade.

In between, there can also be enzymes and other micro-elements which help in the processing of the signal.

Ligand: This can be called as the signaling molecule. A ligand is any molecule which is having a specific function to exerts its action after binding to a specific receptor.

What are the Essential Parts of a Signaling Pathway-a mechanism
All the parts of the signaling pathway: Ligand, Receptor, signaling cascade (enzymes, MAPK) and the ATP. Image of Insulin signaling: By wiki commons

A ligand can be either an endogenous or an exogenous one.

The endogenous ligands include neurotransmitters, hormones, prostaglandins, endorphins, dynorphins, etc. The examples

Exogenous ones mostly include drugs and other externally applied chemicals.

But chemically, most of the exogenous ligands are similar to endogenous ligands. Based on their structure; one can make or find an exogenous ligand for clinical application.

Examples: Acetylcholine, epinephrine and other neurotransmitters.

Receptors: As the name indicates, it is a point in the body to receive a signal. This reception of signal happens only when the ligand is bound to the receptors.

There are four different types of receptors in the human body.

Signal cascade: It can also be called as the biochemical cascade. This involves a few enzymes, ions, and phosphorylation. This cascade gets into action when the ligand acts on the receptor. This mostly leads to physiological responses or products in the body.

This also includes many pathways like the JAK/ STAT pathway, MAPK signaling, hormone signaling.

Essential Parts of a Signaling Pathway
Signaling pathway showing binding of a ligand to the receptor, receptor signal propagation and final production of response.

ATP: Adenosine-triphosphate, is the energy currency of the cell. It is formed in the mitochondria and is essential for the signaling pathway to function. The action of ligands, response of receptors and parts of the signal cascade are dependent on it. Without, ATP (energy), there can be no signal processing and transition. This ATP helps in the chemical modification, movement of ions like Na+1, Ca+2, the release of neurotransmitters at the nerve endings, etc.

Any disease or disorder in the body can be due to deficiency or malfunction of the signaling pathway. Sometimes, it can be due to the breakdown of the whole system itself.

Even, excess signaling and insufficient signaling leads to disturbances in the body homeostasis.

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