PRKAG3 Gene: AMPK Gamma 3 Subunit – Function, Mutations & Clinical Significance

PRKAG3 encodes the gamma-3 regulatory subunit of AMP-activated protein kinase (AMPK), a heterotrimeric complex that acts as a cellular energy sensor. The gamma subunit contains four cystathionine beta-synthase (CBS) domains that bind AMP, ADP, and ATP, regulating AMPK activity in response to energy stress. PRKAG3 is predominantly expressed in skeletal and cardiac muscle, where it modulates glucose uptake, fatty acid oxidation, and glycogen metabolism. Mutations in PRKAG3 are associated with glycogen storage disease and hypertrophic cardiomyopathy.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• AMPK signaling pathway (KEGG: hsa04152)

• Regulation of lipolysis in adipocytes (KEGG: hsa04923)

• Insulin signaling pathway (KEGG: hsa04910)

• Adipocytokine signaling pathway (KEGG: hsa04920)

The PRKAG3 protein (UniProt Q9UGI9) is 489 amino acids long and contains four CBS domains essential for nucleotide binding. It is the muscle-specific gamma subunit of AMPK, forming a complex with alpha and beta subunits. The protein localizes to the cytoplasm and nucleus, and its expression is highest in skeletal and cardiac muscle. Structural studies show that AMP binding induces conformational changes that protect the complex from dephosphorylation, sustaining kinase activity. Mutations in the CBS domains disrupt nucleotide sensing, leading to metabolic dysregulation and glycogen storage disorders.