Question

Beta 2 receptors act via following secondary messenger

• A. Adenylate Cyclase
• B. Tyrosine kinase receptors
• C. TGF-beta receptors
• D. Cytokine receptors

Answer 1

The Correct Option is A

Beta 2 receptors are a type of adrenergic receptor associated with the sympathetic nervous system. They primarily mediate various physiological responses such as bronchial dilation, vasodilation, and metabolic effects. When the beta 2 adrenergic receptors are activated by agonists like adrenaline, they use a specific pathway to elicit cellular responses. This pathway is mediated by a secondary messenger system, which involves the activation of the enzyme adenylate cyclase. The mechanism is as follows:

• The binding of an agonist to the beta 2 receptor activates a G protein.
• This G protein, specifically Gs, stimulates the enzyme adenylate cyclase.
• Adenylate cyclase converts ATP to cyclic AMP (cAMP).
• cAMP acts as a secondary messenger that activates protein kinase A (PKA).
• PKA phosphorylates various target proteins, resulting in the physiological effects associated with beta 2 receptor activation.

The associated options and their functionalities are as follows:

Option	Function
Adenylate Cyclase	Activator of cAMP as a secondary messenger
Tyrosine kinase receptors	Involved in pathways like insulin signaling
TGF-beta receptors	Function via serine/threonine kinase pathways
Cytokine receptors	Typically signal via JAK-STAT pathways

The correct answer is Adenylate Cyclase, as it is the secondary messenger path utilized by beta 2 receptors.