Catalytic subunit of the probable trimeric SNF1-related protein kinase (SnRK) complex, a central regulator of cellular energy homeostasis, which, in response to seemingly unrelated darkness, sugar and stress conditions, activates energy-producing pathways and inhibits energy-consuming processes. May play a role in a signal transduction cascade regulating gene expression and carbohydrate metabolism in higher plants. The SnRK complex may also be involved in the regulation of fatty acid synthesis by phosphorylation of acetyl-CoA carboxylase and in assimilation of nitrogen by phosphorylating nitrate reductase. In vitro, KIN10 exhibits kinase activity on sucrose phosphate synthase and the kinase activity is inhibited by PRL1. May be a subunit of a SCF ubiquitin ligase complex and thus be involved in proteasomal ubiquitination. Phosphorylates GRIK1/SNAK2 and GRIK2/SNAK1 in vitro. Cooperates with FUS3 to regulate developmental phase transitions and lateral organ development and act both as positive regulators of abscisic acid (ABA) signaling during germination. Phosphorylates FUS3 in embryo. Negatively modulates MYC2 accumulation through its protein phosphorylation. Phosphorylates geminivirus (CaLCuV, TGMV, ToMoV) AL2 protein resulting in a delay in the viral DNA accumulation and symptom appearance during infection. Regulates bZIP63 activity to alter metabolism in response to starvation through its protein phosphorylation. Under sugar deprivation conditions, antagonizes the IDD8 function in flowering time control by its protein phosphorylation. Plays a cardinal role in the control of cell proliferation through inhibition of KRP6 activity by its protein phosphorylation. Under submergence, phosphorylates PTP1, leading to the release of the MPK6 signaling pathway inhibition. Triggers its own SUMO-mediated proteasomal degradation, establishing a negative feedback loop that attenuates SnRK1 signaling and prevents detrimental hyperactivation of stress responses. Phosphorylates RAPTOR1B in vitro. Phosphorylates and down-regulates HMGR1S in vitro. Kinase activity is redox-sensitive. Acts upstream of TOR in the regulation of autophagy. Required for the activation of autophagy by many abiotic stresses. Involved in positive regulation of autophagy, possibly by affecting the phosphorylation of ATG1 proteins. Negatively modulates WRI1 accumulation through its protein phosphorylation. Modulates leaf senescence progression by the negative regulation of EIN3 accumulation through its protein phosphorylation. Under extended darkness, C/S1-bZIP-SnRK1 complex interacts with the histone acetylation machinery to remodel chromatin and facilitate transcription. BZIP2-BZIP63-KIN10 complex binds to the ETFQO promoter to up-regulate its transcription. Phosphorylates and down-regulates IPK2b in vitro. Involved in the regulation of sucrose-induced hypocotyl elongation under light/dark cycles.
