G-protein coupled receptors

Definition

G-protein coupled receptors (GPCRs) are a large family of membrane proteins that play a crucial role in cell signaling by transmitting signals from outside the cell to the inside. They are involved in various physiological processes and are targets for a significant number of modern drugs. By binding to specific ligands, GPCRs activate G-proteins, which then initiate a cascade of intracellular events.

5 Must Know Facts For Your Next Test

1. GPCRs are involved in numerous physiological functions, including vision, taste, smell, immune responses, and neurotransmission.
2. These receptors are classified into several families based on their structure and the type of G-proteins they interact with, including the largest family, Class A (rhodopsin-like receptors).
3. Diverse ligands can activate GPCRs, ranging from small molecules to larger proteins, leading to various cellular responses depending on the type of receptor and its associated G-proteins.
4. About 30-50% of all modern medicinal drugs target GPCRs, making them one of the most significant classes of drug targets in pharmacology.
5. The activation of GPCRs leads to changes in intracellular concentrations of second messengers like cyclic AMP (cAMP) or calcium ions, which further propagate the signal within the cell.

Review Questions

• How do g-protein coupled receptors facilitate cellular communication through ligand binding?
  • G-protein coupled receptors facilitate cellular communication by binding specific ligands, such as hormones or neurotransmitters. When a ligand binds to a GPCR, it causes a conformational change in the receptor that activates an associated G-protein. This activation initiates a cascade of intracellular signaling pathways that result in various physiological responses within the cell.
• Discuss the significance of g-protein coupled receptors as drug targets in modern medicine.
  • G-protein coupled receptors are significant drug targets because they are involved in many physiological processes and play key roles in various diseases. Approximately 30-50% of all modern medicinal drugs target GPCRs due to their ability to modulate diverse signaling pathways. This makes GPCRs vital for developing new therapeutic agents aimed at treating conditions like hypertension, depression, and cancer.
• Evaluate the impact of allosteric modulation on g-protein coupled receptors and how it may influence drug discovery.
  • Allosteric modulation can significantly impact g-protein coupled receptors by altering their activity without directly competing with the primary ligand for the binding site. This form of regulation allows for finer control over receptor function and can lead to novel therapeutic strategies in drug discovery. By targeting allosteric sites, researchers can develop drugs that enhance or inhibit receptor activity more precisely, potentially reducing side effects and improving treatment efficacy for various conditions.

Related terms

Ligand: A molecule that binds to a receptor, such as a hormone or neurotransmitter, to initiate a biological response.

Signal transduction: The process by which a cell converts an external signal into a functional response, often involving a series of biochemical events.

Allosteric modulation: The regulation of a receptor's activity through the binding of an effector molecule at a site other than the active site, influencing the receptor's response to its ligand.