Ion channel that contributes to passive transmembrane potassium transport and to the regulation of the resting membrane potential in brain astrocytes, but also in kidney and in other tissues (PubMed:16847696, PubMed:22431633, PubMed:24368895). Forms dimeric channels through which potassium ions pass in accordance with their electrochemical gradient. The channel is selective for K(+) ions at physiological potassium concentrations and at neutral pH, but becomes permeable to Na(+) at subphysiological K(+) levels and upon acidification of the extracellular medium. The homodimer has very low potassium channel activity, when expressed in heterologous systems, and can function as weakly inward rectifying potassium channel (PubMed:9013852, PubMed:24496152). Channel activity is modulated by activation of serotonin receptors (PubMed:24368895). Heterodimeric channels containing KCNK1 and KCNK2 have much higher activity, and may represent the predominant form in astrocytes (PubMed:24496152). Heterodimeric channels containing KCNK1 and KCNK3 or KCNK9 have much higher activity. Heterodimeric channels formed by KCNK1 and KCNK9 may contribute to halothane-sensitive currents (By similarity). Mediates outward rectifying potassium currents in dentate gyrus granule cells and contributes to the regulation of their resting membrane potential (PubMed:25406588). Contributes to the regulation of action potential firing in dentate gyrus granule cells and down-regulates their intrinsic excitability (PubMed:25406588). In astrocytes, the heterodimer formed by KCNK1 and KCNK2 is required for rapid glutamate release in response to activation of G-protein coupled receptors, such as F2R and CNR1 (PubMed:24496152). Required for normal ion and water transport in the kidney (PubMed:16025300). Contributes to the regulation of the resting membrane potential of pancreatic beta cells (PubMed:22431633). The low channel activity of homodimeric KCNK1 may be due to sumoylation. The low channel activity may be due to rapid internalization from the cell membrane and retention in recycling endosomes (PubMed:15540117). Inhibited by quinine, quinidine, barium, and internal acidification. Both activation and channel closure are very rapid. Is not voltage-gated (PubMed:22431633, PubMed:24496152). The relationship between voltage and current is nearly linear (PubMed:22431633, PubMed:24496152). Homodimer; disulfide-linked (PubMed:9013852). Heterodimer with KCNK2; disulfide-linked (PubMed:24496152). In astrocytes, forms mostly heterodimeric potassium channels with KCNK2, with only a minor proportion of functional channels containing homodimeric KCNK1 (By similarity). Interacts with KCNK3 and KCNK9, forming functional heterodimeric channels (By similarity). Interacts with GNG4 (PubMed:24496152). Identified in a complex with PSD and ARF6; interacts only with PSD that is bound to ARF6 (PubMed:15540117). Interacts with UBE2I (By similarity). The heterodimer with KCNK2 is detected at the astrocyte cell membrane (PubMed:24496152). Not detected at the astrocyte cell membrane when KCNK2 is absent (PubMed:24496152). Detected on neuronal cell bodies, and to a lesser degree on neuronal cell projections (PubMed:12855359, PubMed:17079103). Detected on hippocampus dentate gyrus granule cell bodies and to a lesser degree on proximal dendrites (PubMed:25406588). Detected at the apical cell membrane in stria vascularis in the cochlea (By similarity). Detected at the apical cell membrane of vestibular dark cells situated between the crista and the utricle in the inner ear (PubMed:12855359). Detected at the apical cell membrane in stria vascularis in the cochlea (PubMed:12855359). Detected at the apical cell membrane in kidney proximal tubule segment S1 and in subapical compartments in segments S1, S2 and S3 (PubMed:16025300). Predominantly in cytoplasmic structures in kidney distal convoluted tubules and collecting ducts (PubMed:16025300). Predominantly in cytoplasmic structures in hippocampus astrocytes; only a minor proportion of the protein is present at the cell membrane (PubMed:24368895). Detected in spiral ganglion neurons (PubMed:17079103). Detected in hippocampus CA1 and CA1 regions and in the molecular layer of the dentate gyrus (PubMed:24368895, PubMed:25406588). Detected on hippocampus astrocytes (PubMed:24368895, PubMed:24496152). Highly expressed in the stria vascularis in the cochlea (PubMed:12855359). Detected in pancreas islet beta cells (PubMed:22431633). Detected in kidney, at brush border membranes in proximal tubules and in cytoplasmic structures in distal convoluted tubules, thick ascending limbs and collecting ducts (at protein level) (PubMed:15540117, PubMed:16025300). Widely expressed. Detected in spiral ganglion cells (PubMed:17079103). Highest expression in brain, kidney, thyroid, salivary gland, adrenal gland, prostate, epididymis, uterus, placenta, colon and jejunum. Moderate expression in eyes, pituitary, pancreas, smooth muscle, testis and ovary. Very low levels in lung, aorta, liver, heart, skeletal muscle, thymus and spleen. In the brain, highest expression in cerebellar granule cells, brainstem, hippocampus and cerebral cortex (PubMed:18222039). Detected at very low levels in the embryonic central nervous system (PubMed:9559671, PubMed:18222039). Detected as early as 7 days post conception (PubMed:9559671). Detected in dorsal root ganglia, hippocampus, olfactory epithelia and intestine at 19 dpc (PubMed:18222039). Expression in the brain increases strongly 3-8 days after birth, a period of intense postnatal brain development (PubMed:9559671, PubMed:18222039). Detected in dentate granule cells; expression levels show no significant variability during postnatal development (PubMed:18222039). Expression is higher in adults than in neonates (PubMed:9559671, PubMed:18222039). Sumoylation is controversial. Sumoylated by UBE2I. Not sumoylated when expressed in xenopus oocytes or mammalian cells. Sumoylation inactivates the channel, but does not interfere with expression at the cell membrane. Sumoylation of a single subunit is sufficient to silence the dimeric channel. Sumoylation of KCNK1 is sufficient to silence heterodimeric channels formed by KCNK1 and KCNK3 or KCNK9. Desumoylated by SENP1; this activates the channel. Desumoylated by SENP1; this strongly increases halothane-mediated activation of heterodimeric channels formed with KCNK9. SENP1 treatment has no effect. No visible phenotype on standard chow, excepting a lower urinary flow rate (PubMed:16025300). Mice appear normal and are fertile (PubMed:24368895). When kept on a low phosphate diet, both wild-type and mutant mice show strongly reduced urinary phosphate secretion. Still, mutant mice display higher fractional urinary phosphate secretion relative to wild-type, leading to reduced inorganic phosphate levels in blood plasma. The impaired phosphate homeostasis seems to be due to indirect effects on the expression of other transporters, such as SLC34A1 and AQP2 (PubMed:16025300). Principal cells from kidney collecting duct are hyperpolarized, display reduced potassium conductance and strongly reduced quinidine-sensitive potassium channel activity (PubMed:16847696). Besides, collecting ducts from mutant mouse kidney display a larger diameter relative to wild-type (PubMed:16847696). Belongs to the two pore domain potassium channel (TC 1.A.1.8) family.