Serine/threonine protein kinase essential for release from glucose repression (PubMed:3526554, PubMed:6366512, PubMed:3049551, PubMed:1944227, PubMed:8289797, PubMed:8628258, PubMed:25869125). Catalytic subunit of the AMP-activated protein kinase complex also known as the SNF1 kinase complex (Snf1c), a central regulator of cellular energy homeostasis, which, in response to a fall in intracellular ATP levels, activates energy-producing pathways and inhibits energy-consuming processes (PubMed:8289797, PubMed:26667037). The complex phosphorylates histone H3 to form H3S10ph, which promotes H3K14ac formation, leading to transcriptional activation through TBP recruitment to the promoters (PubMed:15719021). The complex also negatively regulates the HOG1 MAPK pathway in ER stress response including unfolded protein response (UPR) (PubMed:25730376, PubMed:26394309). Under nutrient/energy depletion, the complex phosphorylates and activates PAS kinase PSK1 which in turn activates PBS1, leading to the inhibition of the TORC1 signaling pathway (PubMed:25428989). SNF1 also interacts and phosphorylates adenylate cyclase CYR1 and negatively regulates the protein kinase A signaling pathway (PubMed:26309257). Also phosphorylates and regulates the transcriptional activator CAT8 (PubMed:15121831). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] The kinase activity is positively regulated by SNF4 via sequestration of the SNF1 auto-inhibitory domain (AID) (PubMed:2557546, PubMed:17851534). Component of the AMP-activated protein kinase complex also known as the SNF1 kinase complex (Snf1c), a heterotrimeric complex composed of an alpha subunit (SNF1), a regulatory subunit beta (GAL83 and substoichiometric alternate beta subunits SIP1 and SIP2), and a regulatory subunit gamma (SNF4) (PubMed:2557546, PubMed:2481228, PubMed:7813428, PubMed:9121458, PubMed:15719021, PubMed:17851534). Interacts with the transcriptional activator SIP4 (PubMed:8628258). Interacts with SAK1 (PubMed:12748292, PubMed:16847059). Interacts with CTK1 (PubMed:16182287): Interacts with adenylate cyclase CYR1 (PubMed:26309257). Nuclear translocation occurs under nitrogen and glucose starvation conditions (PubMed:25869125). Expression of the SNF1 gene itself is not glucose repressible (PubMed:6366513). The regulatory domain (RS) also called auto-inhibitory domain (AID) inhibits kinase activity of the protein kinase domain (KD) (PubMed:19474788, PubMed:20823513). The AID is sequestered by SNF4 within the AMP-activated protein kinase complex which might correspond to the activated SNF1 form (PubMed:17851534). The ubiquitin-associated domain (UBA) localized within the AID dampens kinase activation, probably by restraining SNF1-SNF4 associations (PubMed:25869125). Moreover, the UBA domain influences life span in a FKH1- and FKH2-dependent mechanism (PubMed:25869125). Phosphorylation at Thr-210 in response to glucose limitation leads to activation of kinase activity (PubMed:11486005, PubMed:12748292). ADP, but not AMP, protects the enzyme from dephosphorylation at Thr-210 by GLC7 (PubMed:22019086). Sumoylation by the SUMO (E3) ligase MMS21 leads to inhibition by interaction of SUMO attached to Lys-549 with a SUMO-interacting sequence motif located near the active site of SNF1, and by targeting SNF1 for glucose-induced destruction via the SLX5-SLX8 (SUMO-directed) ubiquitin ligase (PubMed:24108357). Present with 589 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.