G protein-coupled purinergic nucleotide receptor activity

Definition

Target type: molecularfunction

Combining with a purine nucleotide 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:mah, PMID:9755289]

G protein-coupled purinergic nucleotide receptors (P2Y receptors) are a family of transmembrane proteins that bind extracellular nucleotides, such as adenosine triphosphate (ATP) and adenosine diphosphate (ADP), and initiate intracellular signaling pathways. These receptors play crucial roles in a wide range of physiological processes, including inflammation, neurotransmission, vascular tone regulation, and cell growth.

The molecular function of G protein-coupled purinergic nucleotide receptor activity involves the following steps:

1. **Ligand Binding:** Extracellular nucleotides bind to the extracellular domain of the receptor, triggering a conformational change in the protein.
2. **G Protein Activation:** The conformational change in the receptor activates a heterotrimeric G protein, which is composed of alpha, beta, and gamma subunits. Upon activation, the alpha subunit dissociates from the beta and gamma subunits, exchanging GDP for GTP.
3. **Second Messenger Production:** The activated alpha subunit interacts with downstream effector proteins, such as phospholipase C (PLC), adenylyl cyclase, or ion channels, leading to the production of intracellular second messengers, such as inositol triphosphate (IP3), diacylglycerol (DAG), and cyclic AMP (cAMP).
4. **Signal Transduction:** The second messengers activate downstream signaling cascades, ultimately leading to a variety of cellular responses, such as muscle contraction, changes in gene expression, and altered cell behavior.

Specifically, the molecular function of G protein-coupled purinergic nucleotide receptor activity involves:

- **Ligand recognition and binding:** P2Y receptors exhibit high affinity for specific nucleotide ligands, such as ATP, ADP, UDP, and UTP. This selectivity is crucial for the precise regulation of cellular signaling pathways.
- **Conformational changes:** Upon ligand binding, the receptor undergoes conformational changes, exposing intracellular binding sites for G protein interaction.
- **G protein coupling and activation:** P2Y receptors activate specific subtypes of G proteins, including Gq/11, Gi/o, and Gs, depending on the receptor subtype.
- **Effector protein activation:** Activated G proteins initiate intracellular signaling pathways by activating downstream effector proteins, such as PLC, adenylyl cyclase, and ion channels.
- **Signal amplification:** The activation of effector proteins triggers the production of second messengers, which further amplify the initial signal.
- **Cellular responses:** The second messengers regulate a wide range of cellular responses, including cell proliferation, differentiation, apoptosis, and secretion.

The molecular function of G protein-coupled purinergic nucleotide receptor activity is highly complex and involves a series of interconnected events, from ligand binding to cellular response. Understanding these intricate mechanisms is essential for developing novel therapies targeting P2Y receptors for various diseases.'
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Proteins (8)

Compounds (97)