Catalyzes the phosphorylation of sphingosine to form sphingosine-1-phosphate (SPP), a lipid mediator with both intra- and extracellular functions (PubMed:16118219, PubMed:17346996, PubMed:21084291). Also acts on D-erythro-dihydrosphingosine, D-erythro-sphingosine and L-threo-dihydrosphingosine. Binds phosphoinositides (PubMed:16118219, PubMed:10751414). In contrast to prosurvival SPHK1, has a positive effect on intracellular ceramide levels, inhibits cells growth and enhances apoptosis (PubMed:16118219). In mitochondria, is important for cytochrome-c oxidase assembly and mitochondrial respiration. The SPP produced in mitochondria binds PHB2 and modulates the regulation via PHB2 of complex IV assembly and respiration (PubMed:20959514). In nucleus, plays a role in epigenetic regulation of gene expression. Interacts with HDAC1 and HDAC2 and, through SPP production, inhibits their enzymatic activity, preventing the removal of acetyl groups from lysine residues with histones. Up-regulates acetylation of histone H3-K9, histone H4-K5 and histone H2B-K12. In nucleus, may have an inhibitory effect on DNA synthesis and cell cycle (By similarity). In mast cells, is the main regulator of SPP production which mediates calcium influx, NF-kappa-B activation, cytokine production, such as TNF and IL6, and degranulation of mast cells (PubMed:17346996). In dopaminergic neurons, is involved in promoting mitochondrial functions regulating ATP and ROS levels (PubMed:25637806). Also involved in the regulation of glucose and lipid metabolism (PubMed:30593892). a sphingoid base + ATP = a sphingoid 1-phosphate + ADP + H(+) ATP + sphing-4-enine = ADP + H(+) + sphing-4-enine 1-phosphate ATP + sphinganine = ADP + H(+) + sphinganine 1-phosphate (4R)-hydroxysphinganine + ATP = (4R)-hydroxysphinganine 1-phosphate + ADP + H(+) Optimum pH is 7.5. Interacts with histone H3. Interacts with HDAC1, HDAC2, MBD2 and SIN3A. Interacts with EEF1A1; the interaction enhances SPHK2 kinase activity (By similarity). Interacts with PHB2 (PubMed:20959514). In nucleus, is located in nucleosomes where it associates with core histone proteins such as histone 3. In apoptotic cells, colocalizes with CASP1 in cell membrane where is cleaved and released from cells in an active form. Expressed in heart, brain, liver, kidney and testis (PubMed:10751414). Expressed by mast cells (at protein level) (PubMed:17346996). In the substantia nigra, expressed by dopaminergic neurons (at protein level) (PubMed:25637806). At 10.5 dpc, expression is relatively ubiquitous with the strongest signals detected in the limb buds, eyes and branchial arches and a weaker expression in the telencephalon and spinal cord. Expressopm decreases upon treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) which is used to induce Parkinson disease in mouse model. Phosphorylated by PKD on Ser-384 and Ser-386 upon PMA treatment. Phosphorylation induces export from the nucleus to the cytoplasm. Phosphorylated by MAPK1 and MAPK2 at Thr-578, phosphorylation is induced by agonists such as EGF and PMA and increases kinase activity. Cleaved by CASP1 in apoptotic cells. The truncated form is released from cells. Mutant mice are viable, fertile and have normal longevity. They show reduced SPP levels (PubMed:16314531). Mice have decreased fat mass but increased lean mass, they display increased energy expenditure compared to wild-type. Aging mice are protected from metabolic decline and obesity. 52-week old male mutant mice have decreased weight and fat mass, and increased glucose tolerance and insulin sensitivity compared to control mice (PubMed:30593892). Double knockout for SPHK1 and SPHK2 causes embryonic lethality (PubMed:16314531). Between 11.5 dpc and 12.5 dpc embryos exhibit cranial hemorrhage and die at 13.5 dpc (PubMed:16314531). At 11.5 dpc the wall of the dorsal aorta is poorly developed and endothelial cells are severely defective in all blood vessels in the mesenchymal region of the head (PubMed:16314531). Embryos also show a neural tube defect (PubMed:16314531).