AMPK is a complex heterotrimeric structure, which consists of one catalytic subunit and two regulatory subunits. The α subunits (α1 and α2) are catalytic subunits, with a molecular weight of 63KD.  β and γ subunits are regulatory subunits, β subunit has β1, β2 isoforms;  γ subunit has γ1, γ2, γ3 isoforms.  AMPK is widely present in eukaryotic cells.

AMPKα1 is mainly distribute in liver, kidney, heart, lung, brain and islet β-cells.  

Ampkα2 is mainly distribute in skeletal muscle, heart and liver.  In terms of cell distribution, AMPKα1 and AMPKα2 are also different, AMPKα1 is mainly distributed in the cytoplasm, while AMPKα2 is mainly present in the nucleus.  

AMPK activity is regulated by the energy change in the cell and is a monitor of the energy change in the cell, mainly regulated by the AMP/ATP ratio in the cell.  Under normal conditions, the AMP/ATP ratio remains stable to maintain the basic metabolic energy requirements of the cell. When the cell is in a state of stress, such as ischemia, hypoxia, starvation, intracellular PH change, oxidative stress and increased creatine/phosphate ratio, the AMP/ATP ratio increases.  Thus, AMPK is activated, which causes the activation or inhibition of downstream signaling molecules, reduces anabolic metabolism, promotes catabolic process, improves ATP generation, and restores the AMP/ATP ratio to normal and maintains stability.  

AICAR AMPK activitor is an adenosine analogue, which can be catalyzed by adenosine kinase to form its single nucleotide derivative ZMP in vivo or in cells. ZMP has an AMP-like effect, thereby causing the increase of AMP/ATP ratio and the activation of AMPK.