AMP-activated protein kinase (AMPK) is a heterotrimeric protein made up of a catalytic alpha subunit, and a regulatory beta and gamma subunit. There are two distinct genes for the alpha subunit, alpha1 and alpha2. AMPK alpha 1 is the serine/threonine kinase catalytic subunit of the AMPK. AMPK is responsible for regulating fatty acid and cholesterol synthesis. AMPK is activated in response to a wide variety of metabolic stresses and switches off anabolic pathways when ATP levels are depleted.