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Anonymous
more than 3 weeks ago

Describe G-protein coupled receptors that activate adenylyl cyclase?

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ChatGPT
more than 3 weeks ago
G-protein coupled receptors (GPCRs) that activate adenylyl cyclase are a type of cell surface receptor that are involved in signal transduction. When these receptors are activated by a ligand, such as a hormone or neurotransmitter, they trigger a series of events that ultimately lead to the production of cyclic adenosine monophosphate (cAMP) by adenylyl cyclase.

The activation of adenylyl cyclase by GPCRs involves a complex signaling pathway. When the ligand binds to the receptor, it causes a conformational change in the receptor that allows it to interact with a G protein. The G protein then activates adenylyl cyclase, which catalyzes the conversion of ATP to cAMP. cAMP then acts as a second messenger, activating downstream signaling pathways that regulate various cellular processes.

Overall, GPCRs that activate adenylyl cyclase play a crucial role in mediating cellular responses to extracellular signals and are involved in a wide range of physiological processes, including neurotransmission, hormone signaling, and immune responses.
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Google Gemini AI
more than 3 weeks ago
G-protein Coupled Receptors (GPCRs) that Activate Adenylyl Cyclase

GPCRs are a large family of transmembrane proteins that bind to extracellular ligands and activate intracellular signaling pathways. Certain GPCRs specifically couple to the G protein Gαs, leading to the activation of adenylyl cyclase (AC) and downstream cAMP signaling.

These GPCRs are characterized by the following features:

Structure:

- Seven transmembrane alpha-helical domains
- N-terminal extracellular domain
- C-terminal cytoplasmic domain
- Multiple glycosylation sites

Ligands:

- Various hormones, neurotransmitters, and other signaling molecules

Mechanism of Activation:

1. Ligand Binding: Ligand binding to the extracellular domain causes a conformational change in the GPCR.
2. Gαs Activation: This conformational change allows Gαs to bind to the cytoplasmic domain of the GPCR. GDP bound to Gαs is exchanged for GTP, causing Gαs to dissociate from Gβγ subunits.
3. Adenylyl Cyclase Activation: Gαs-GTP directly interacts with AC, stimulating its enzymatic activity.

Examples:

- β2-adrenergic receptor (β2AR): Binds to epinephrine and norepinephrine to stimulate AC and increase cAMP levels in the heart, lungs, and other tissues.
- Ghrelin receptor: Binds to ghrelin to activate AC in the hypothalamus, promoting appetite and energy intake.
- Dopamine D1 receptor (D1R): Binds to dopamine to activate AC in the basal ganglia, modulating motor control and cognition.

Physiological Effects:

The activation of AC by GPCRs leads to increased cAMP production, which has a wide range of physiological effects, including:

- Vasodilation
- Smooth muscle relaxation
- Cardiac stimulation
- Increased metabolic activity
- Neuronal excitation

Therapeutic Significance:

GPCRs that activate AC are targets for numerous therapeutic drugs, including:

- β-adrenergic agonists (e.g., albuterol) for asthma and heart failure
- Dopamine agonists (e.g., levodopa) for Parkinson's disease
- Ghrelin antagonists (e.g., octreotide) for acromegaly
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