G-protein coupled receptors

Definition

G-protein coupled receptors (GPCRs) are a large family of membrane proteins that play a crucial role in transmitting signals from outside the cell to its interior. They are involved in various physiological processes and serve as targets for many therapeutic drugs, making them key players in the mechanisms of drug action and receptor binding.

5 Must Know Facts For Your Next Test

1. GPCRs are involved in numerous cellular processes, including vision, taste, and neurotransmission.
2. Approximately 30% of all modern medicinal drugs target GPCRs due to their central role in signal transduction.
3. When a ligand binds to a GPCR, it causes a conformational change that activates an associated G-protein, which then interacts with other intracellular signaling pathways.
4. The activation of GPCRs can lead to diverse cellular responses, depending on the type of G-protein activated (e.g., Gs, Gi, or Gq).
5. GPCRs can also undergo desensitization, where prolonged exposure to a ligand reduces their responsiveness, impacting drug efficacy.

Review Questions

• How do GPCRs facilitate communication between external signals and internal cellular processes?
  • GPCRs function as critical mediators in signal transduction by binding ligands outside the cell, which then induces a conformational change in the receptor. This change activates an associated G-protein that relays the signal to various intracellular pathways. This process allows cells to respond to hormones, neurotransmitters, and other signaling molecules effectively.
• What role do second messengers play in the signaling pathway initiated by GPCR activation?
  • Second messengers are pivotal in amplifying the signal generated by activated GPCRs. Once a GPCR is activated by a ligand and interacts with a G-protein, this can lead to the production or release of second messengers like cyclic AMP (cAMP) or inositol triphosphate (IP3). These second messengers propagate the signal further within the cell, ultimately leading to various physiological responses.
• Evaluate the impact of GPCR desensitization on drug development and therapeutic strategies.
  • GPCR desensitization poses significant challenges in drug development as prolonged ligand exposure can lead to reduced receptor responsiveness, affecting therapeutic outcomes. Understanding this phenomenon is crucial for creating drugs that either prevent desensitization or act on alternative pathways. This evaluation highlights the importance of considering receptor dynamics in developing effective treatments for various conditions, particularly those involving chronic disease states.

Related terms

Ligands: Molecules that bind to receptors, including GPCRs, to initiate a physiological response.

Second Messengers:

Intracellular signaling molecules that are activated by GPCRs and help amplify the signal within the cell.

Agonists:

Substances that activate GPCRs, mimicking the action of natural ligands and triggering a biological response.