5'-AMP-activated protein kinase subunit gamma CBS domains (AMPK gamma CBS domains)

The CBS (Cystathionine Beta-Synthase) domains of the AMP-activated protein kinase (AMPK) gamma subunit serve as the primary energy-sensing module of the AMPK heterotrimer. These domains are organized into two Bateman folds, creating four potential binding sites for adenine nucleotides (AMP, ADP, and ATP), which allow the enzyme to monitor the cellular energy charge (Hardie et al., 2012). In humans, three of these sites are functional and competitively bind nucleotides; when the AMP:ATP ratio rises during energy stress, AMP or ADP displaces ATP, triggering a conformational change that allosterically activates the complex and prevents the dephosphorylation of the activating Thr172 residue on the alpha subunit (Xiao et al., 2011; Oakhill et al., 2011). This activation shifts cellular metabolism from ATP-consuming anabolic pathways to ATP-generating catabolic pathways, such as fatty acid oxidation and glucose uptake. While pharmacological activation of these domains is a key strategy for treating metabolic diseases like type 2 diabetes, certain mutations in the gamma-2 subunit (PRKAG2) are linked to Wolff-Parkinson-White syndrome and hypertrophic cardiomyopathy, characterized by abnormal glycogen storage (Gollob et al., 2001). Consequently, the CBS domains are critical targets for metabolic modulation, requiring careful consideration of tissue-specific effects and isoform selectivity.

Other names

AMPK gamma subunitBateman domainsCystathionine beta-synthase domains of AMPKPRKAG1/2/3 CBS domainsAMP-activated protein kinase regulatory subunit gamma

Binding of AMP or ADP to the CBS domains induces a conformational change in the AMPK heterotrimer that allosterically activates the kinase and protects the catalytic alpha-subunit from dephosphorylation at Thr172 by protein phosphatases.