Question

Which of the following factors that are part of the β

-adrenergic receptor-adenylyl cyclase pathway when has a mutation of loss of function will increase glucose levels?

  

Phosphatase

Glycogen phosphorylase

Protein Kinase A (PKA)

Adenylyl cyclase

Receptor for epinephrine/glucagon

Answer 1

Beta adrenergic receptor adynylyl cyclase also known as ADRB2 . Stimulation of the cascade caused an accumulation of the second messenger cAMP and activated via the cAMP the cAMP dependent protein kinase A i.e PKA. The PKA phosphorylated, beside other cell proteins, the beta adrenergic receptors. Beta adrenergic receptors couple to G​​​​​​s and activate adynylyl cyclase.

Loss of function mutation have a high risk of glucose levels increase, recessive mutations inactive the affected gene and lead to a loss of function. Sometimes this is because the mutations used are not part of a switch regulation pathway but instead a complex pathway are more often rule than the exception. Glucose signalling activates phosphatase 2 A . These findings have significant implications for modulation of mitogenic and proapoptatic actions of beta - AR pathways.

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