A1 adenosine receptor binding

Definition

Target type: molecularfunction

Binding to an A1 adenosine receptor. [GOC:mah, GOC:nln]

The A1 adenosine receptor (A1AR) is a G protein-coupled receptor (GPCR) that binds adenosine, a ubiquitous nucleoside. Upon adenosine binding, A1AR triggers a cascade of intracellular signaling events leading to a wide range of physiological effects. The molecular function of A1AR binding can be summarized as follows:

1. **Ligand Binding:** Adenosine, the endogenous ligand for A1AR, binds to the receptor's extracellular domain, inducing a conformational change in the receptor structure.

2. **G Protein Activation:** The conformational change in A1AR activates the associated G protein, specifically the Gi/o protein. This activation involves the exchange of GDP for GTP on the G protein's alpha subunit.

3. **Signal Transduction:** The activated G protein alpha subunit, Gi/oα, dissociates from the receptor and interacts with downstream effector proteins.

4. **Inhibition of Adenylyl Cyclase:** The Gi/oα subunit directly inhibits the activity of adenylyl cyclase, an enzyme responsible for producing cyclic AMP (cAMP). This results in a decrease in intracellular cAMP levels.

5. **Activation of Potassium Channels:** The Gi/oα subunit also directly activates potassium (K+) channels, leading to an efflux of potassium ions from the cell.

6. **Inhibition of Calcium Channels:** Additionally, the Gi/oα subunit can indirectly inhibit calcium (Ca2+) channels through the activation of phospholipase C (PLC), which generates inositol trisphosphate (IP3), a second messenger that triggers Ca2+ release from intracellular stores.

7. **Modulation of Neuronal Activity:** The downstream signaling events triggered by A1AR activation, including decreased cAMP levels, increased potassium efflux, and decreased calcium influx, collectively contribute to the modulation of neuronal activity. This includes reducing neuronal excitability, suppressing neurotransmitter release, and influencing synaptic plasticity.

8. **Regulation of Cardiovascular Function:** A1AR activation plays a crucial role in regulating cardiovascular function. The receptor's activation leads to bradycardia (slowed heart rate), vasodilation (dilation of blood vessels), and decreased blood pressure.

9. **Anti-inflammatory Effects:** A1AR activation has been shown to exert anti-inflammatory effects by inhibiting the production of pro-inflammatory cytokines such as TNF-α and IL-1β.

10. **Neuroprotective Effects:** A1AR activation has been implicated in neuroprotective effects, including reducing neuronal damage caused by ischemia, excitotoxicity, and oxidative stress.

Overall, the molecular function of A1AR binding is complex and multifaceted. It involves a cascade of signaling events that ultimately lead to a diverse range of physiological effects, including modulation of neuronal activity, regulation of cardiovascular function, anti-inflammatory actions, and neuroprotective properties.'
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Proteins (3)

Compounds (43)