PRKAG2 and chronic obstructive pulmonary disease: PRKAG2 (Protein kinase AMP-activated non-catalytic subunit gamma 2) encodes for a sub-unit of the AMP-activated protein kinase (AMPK) enzyme, a central regulator of cellular energy metabolism implicated in COPD in several ways (e.g., compensation for mitochondrial dysfunction, regulation of oxidative stress and smooth muscle contraction).