Question

Which of the following best describes the function of AMP-dependent protein kinase (AMPK)?

a. It activates biosynthetic pathways and inhibits metabolic pathways that generate ATP.

b. It activates both ATP-generating and biosynthetic pathways.

c. It inhibits both ATP-generating and biosynthetic pathways

d. It activates metabolic pathways that generate ATP and inhibits biosynthetic pathways.

Answer 1

Ans.

• A key responsibility of AMP-dependent protein kinase (AMPK) is to work as a master regulator of maintaining homeostasis of cellular energy.
• Stressed situations like low concentration of glucose, hypoxia, heat shock and ischemia, which lowers the cellular ATP level cause activation of AMPK.
• It is found as a heterotrimeric complex comprising of an alpha subunit (catalytic in nature) and two regulatory subunits - beta and gamma.
• Because of it's role as a regulator of cellular energy homeostasis, activation of AMPK in the conditions of low ATP level causes positive regulation of certain signaling pathways.
• Activation of these signaling (metabolic) pathways including autophagy and oxidation of fatty acids, by AMPK restores the cellular supplies of ATP.
• Biosynthetic processes which consumes ATP such as gluconeogenesis, lipid and protein synthesis, are negatively regulated (inhibited) by AMPK.
• These effects by AMPK are brought by direct phosphorylation of several enzymes participating in these processes and also through control of metabolic pathways at transcriptional level.
• Because of it's central role as a master regulator of metabolism of both, lipid as well as glucose, AMPK is being evaluated as a potential therapeutic target in many metabolic diseases such as type 2 DM, obesity and cancer.