The AMPK-RK family comprises AMP-activated protein kinases (AMPKs), MAP/microtubule affinity-regulating kinases (MARKs), Brain-specific kinases (BRSKs), Salt inducible kinases (SIKs), maternal embryonic leucine zipper kinase (MELK), and SNF-related serine/threonine-protein kinase (SNRK). It is the only kinase family in the human genome containing an ubiquitin-associated (UBA) or UBA-like domain which is located immediately C-terminal to their N-terminal protein kinase catalytic domain. In addition, most of family members contain a C-terminal regulatory domain of 5'-AMP-activated protein kinase (AMPK), but some are lack of this region. AMPK-RKs play central roles in metabolic control, energy homeostasis and stress responses in eukaryotes. They require phosphorylation by liver kinase B1 (LKB1) for full activity. Normally, AMPK-RKs appear to exist as heterotrimeric complexes consisting of a catalytic alpha-subunit and regulatory beta- and gamma-subunits. This model corresponds to the catalytic subunit. The UBA domain, previously called SNF1 homology (SNH) domain, regulates the conformation, LKB1-mediated phosphorylation and activation, and localization of the AMPK-RKs, but does not interact with ubiquitin-like molecules. In AMPKalpha subunits, the UBA-like autoinhibitory domain (AID) is responsible for AMPKalpha subunit autoinhibition. Due to the lack of UBA domain, NUAK1 kinase, also called ARK5 (AMPK-related kinase 5), and NUAK2 kinase, also called SNARK (SNF1/AMPK-related kinase), are not included in this family.
Jiyao W et al.(2023). "The conserved domain database in 2023.",