What is the function of a receptor?

Functions of a Receptor:

1. Receptors are proteins that bind to external messengers to create a series of downstream effects that mediate a specific response in the cell.
2. Receptors have a ligand-binding domain that recognizes the specific ligand and the effector domain that undergoes conformational changes to produce a downstream event.
3. The types of receptors and their respective function is described below:

• Ligand-gated ion channels:
  1. These are ion channels that upon ligand binding open or close to allow certain ions such as sodium, potassium, etc., to pass through.
  2. These types of channels are found in neurons and muscle cells. For example, acetylcholine receptors.
• G-protein coupled receptors (GPCRs):
  1. These are the largest family of receptors having a G-protein bound on the cytoplasmic side.
  2. The binding of the ligand triggers a series of intracellular events that regulate the function of various proteins or ion channels.
  3. For example, adrenergic receptors in the heart are GPCRs.
• Catalytic receptors:
  1. They activate or inactivate proteins by either phosphorylating or dephosphorylating them.
  2. For example, erythropoietin receptor.
• Nuclear receptors:
  1. Unlike the above-mentioned receptors, nuclear receptors are located inside the cell and are transcription factors.
  2. Steroid hormones bind nuclear receptors which then move into the nucleus and bind to DNA to either induce or suppress gene expression.