G protein-coupled peptide receptor activity

Definition

Target type: molecularfunction

Combining with a peptide and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. [GOC:dph, GOC:tb]

G protein-coupled peptide receptor activity is a molecular function that involves the binding of peptides to a specific receptor, which is a transmembrane protein embedded in the cell membrane. This binding event initiates a signaling cascade within the cell, leading to a wide range of cellular responses. Here is a detailed explanation:

1. **Ligand Binding:** Peptides, which are short chains of amino acids, bind to the extracellular domain of the G protein-coupled peptide receptor (GPCR). This binding event is highly specific, ensuring that only the appropriate peptide ligand can activate the receptor.
2. **Conformational Change:** Upon ligand binding, the receptor undergoes a conformational change. This change in shape alters the receptor's intracellular domain, which interacts with a heterotrimeric G protein located on the inner surface of the cell membrane.
3. **G Protein Activation:** The conformational change in the GPCR causes the G protein to dissociate into its alpha, beta, and gamma subunits. The alpha subunit, which was previously bound to GDP, releases GDP and binds GTP. This GTP-bound alpha subunit then detaches from the beta and gamma subunits.
4. **Signaling Cascade:** The activated alpha subunit of the G protein interacts with downstream effector molecules, such as adenylyl cyclase, phospholipase C, or ion channels. These effector molecules generate second messengers, which amplify and propagate the signal within the cell.
5. **Cellular Response:** The second messengers activate various intracellular signaling pathways, ultimately leading to a specific cellular response. This response can be diverse and depends on the particular receptor and cell type. Examples include changes in gene expression, cell proliferation, differentiation, or apoptosis.

In summary, G protein-coupled peptide receptor activity is a complex process that involves ligand binding, receptor activation, G protein dissociation, effector activation, and second messenger production. This process plays a crucial role in mediating cellular responses to a wide range of peptide ligands, impacting diverse physiological functions.'
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Proteins (24)

Compounds (129)