PRKAA1

PRKAA1 Full Name

protein kinase, AMP-activated, alpha 1 catalytic subunit

PRKAA1 Introduction

PRKAA1 (protein kinase AMP‑activated catalytic subunit alpha 1) encodes the α1 catalytic subunit of the AMP‑activated protein kinase (AMPK), a central regulator of cellular energy homeostasis. The gene is located on human chromosome 5p13.1 and produces a protein of approximately 548 amino acids with a molecular weight of about 63 kDa. PRKAA1 is ubiquitously expressed in all mammalian tissues, with particularly high levels in the liver, skeletal muscle, heart, and brain. AMPK functions as a heterotrimeric complex composed of a catalytic α subunit (α1 or α2, encoded by PRKAA1 and PRKAA2, respectively), a scaffolding β subunit (β1 or β2), and a regulatory γ subunit (γ1, γ2, or γ3). Upon sensing increases in cellular AMP/ADP to ATP ratios (i.e., energy stress), AMPK is activated and phosphorylates numerous downstream targets to switch off anabolic pathways (fatty acid synthesis, protein synthesis, gluconeogenesis) and switch on catabolic pathways (fatty acid oxidation, glycolysis, autophagy). PRKAA1 is essential for metabolic adaptation to exercise, fasting, and hypoxia, and its dysregulation is implicated in metabolic syndrome, type 2 diabetes, cancer, and neurodegenerative diseases.

Figure 1. Strcuture of PRKAA1.

Structural Domains and Activation Mechanism
PRKAA1 contains several conserved domains. The N‑terminal kinase domain (approximately 270 amino acids) harbors the catalytic site, including the critical threonine residue (Thr172) within the activation loop. Phosphorylation of Thr172 by upstream kinases (LKB1, CaMKKβ, or TAK1) is essential for full enzymatic activity. The autoinhibitory domain (AID) lies immediately C‑terminal to the kinase domain and blocks substrate access in the absence of activating signals. The C‑terminal β‑subunit binding domain mediates interaction with the β subunit of the AMPK heterotrimer. Additionally, PRKAA1 contains a C‑terminal tail that interacts with the γ subunit and is involved in allosteric regulation by AMP. Unlike PRKAA2, which is predominantly nuclear, PRKAA1 is primarily cytoplasmic, though both isoforms shuttle between compartments depending on cellular context. The three‑dimensional structure of the PRKAA1 kinase domain in complex with AMP has been solved, revealing conformational changes that protect Thr172 from dephosphorylation.

Metabolic Functions and Downstream Targets
PRKAA1 coordinates a broad metabolic network to restore energy balance. Upon activation, it phosphorylates and inactivates acetyl‑CoA carboxylase (ACC1 and ACC2) , reducing malonyl‑CoA levels and thereby promoting fatty acid oxidation (via CPT1) while inhibiting fatty acid synthesis. It phosphorylates HMG‑CoA reductase to suppress cholesterol synthesis. In the liver, PRKAA1 inhibits gluconeogenesis by phosphorylating CRTC2 (which blocks CREB activity) and by promoting the degradation of PEPCK. In muscle, it enhances glucose uptake by promoting translocation of GLUT4 vesicles and activates glycolysis via phosphofructokinase‑2 (PFK2). PRKAA1 also regulates autophagy through phosphorylation of ULK1 and beclin‑1, and it controls protein synthesis by phosphorylating TSC2 (activating the tumor suppressor) and Raptor (inhibiting mTORC1). In addition, PRKAA1 modulates mitochondrial biogenesis by activating PGC‑1α. This wide array of substrates explains why AMPK activation has beneficial effects on insulin sensitivity, lipid profiles, and body weight.

Alternate Names for PRKAA1

PRKAA1; protein kinase, AMP-activated, alpha 1 catalytic subunit; AMPK; AMPKa1; 5-AMP-activated protein kinase catalytic subunit alpha-1; ACACA kinase; AMPK alpha 1; HMGCR kinase; AMPK subunit alpha-1; tau-protein kinase PRKAA1; acetyl-CoA carboxylase kinase; AMP -activate kinase alpha 1 subunit; hydroxymethylglutaryl-CoA reductase kinase; AMP-activated protein kinase, catalytic, alpha-1; 5-AMP-activated protein kinase, catalytic alpha-1 chain;