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C-terminal regulatory domain of 5'-AMP-activated protein kinase (AMPK) alpha catalytic subunit AMPK, a serine/threonine protein kinase (STK), catalyzes the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. It acts as a sensor for the energy status of the cell and is activated by cellular stresses that lead to ATP depletion such as hypoxia, heat shock, and glucose deprivation, among others. AMPK is a heterotrimer of three subunits: alpha, beta, and gamma. Co-expression of the three subunits is required for kinase activity; in the absence of one, the other two subunits get degraded. The AMPK alpha subunit is the catalytic subunit and it contains an N-terminal kinase domain and a C-terminal regulatory domain (RD). Vertebrates contain two isoforms of the alpha subunit, alpha1 and alpha2, which are encoded by different genes, PRKAA1 and PRKAA2, respectively. The C-terminal RD of the AMPK alpha subunit is involved in AMPK heterotrimer formation. It mainly interacts with the C-terminal region of the beta subunit to form a tight alpha-beta complex that is associated with the gamma subunit. The AMPK alpha subunit RD also contains an auto-inhibitory region that interacts with the kinase domain; this inhibition is negated by the interaction with the AMPK gamma subunit. AMPK is conserved throughout evolution; the AMPK alpha subunit homologs in yeast and plants are called Snf1 and SnRK1 (Snf1 related kinase), respectively. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",