lAMPK

lAMPK is a term occasionally used to refer to hepatic AMPK, the liver-expressed form of AMP-activated protein kinase. AMPK is a heterotrimeric serine/threonine kinase composed of catalytic α subunits (α1 or α2) and regulatory β and γ subunits. While AMPK is widespread, the specific subunit composition can vary by tissue, and in the liver this complex integrates metabolic signals to maintain energy balance.

Activation of hepatic AMPK occurs in response to energy stress, marked by increases in AMP or ADP relative to ATP. Activation involves phosphorylation of Thr172 in the α subunit by upstream kinases such as LKB1 and, in some contexts, CaMKKβ. Hepatic AMPK is also regulated by hormones and nutrients; pharmacological activators like metformin and AICAR can stimulate hepatic AMPK, linking cellular energy status to whole‑body glucose and lipid metabolism.

In the liver, activated AMPK promotes catabolic pathways that generate ATP and inhibits anabolic processes that consume energy. It increases fatty acid oxidation and inhibits lipogenesis by phosphorylating and inhibiting acetyl-CoA carboxylase and other lipogenic enzymes. It also modulates cholesterol synthesis, gluconeogenesis, and glucose output, in part through effects on transcription factors and signaling pathways such as SREBP-1c and mTORC1. Through these actions, hepatic AMPK contributes to overall metabolic homeostasis and insulin sensitivity and is implicated in conditions such as nonalcoholic fatty liver disease and type 2 diabetes.

Nomenclature varies, and not all sources use the term lAMPK. When used, it typically denotes the liver-enriched or liver-specific aspects of the AMPK complex, distinct from isoform usage in other tissues.