KCNK18
Domain
Each subunit contributes two pore-forming domains 1 and 2 which assemble to form a single pore with M2 and M4 transmembrane helices lining the central cavity and M1 and M3 facing the lipid bilayer. The transmembrane helices are bridged by the selectivity filters 1 and 2 carrying a signature sequence TxTTxGYGD that coordinate the permeant ions. Up to four ions can simultaneously occupy the selectivity filter and at least two elementary charges must translocate across the filter to convert it into the open conformation.
Function
K(+) channel that conducts outward and inward rectifying currents at depolarized and hyperpolarized membrane potentials, respectively. The outward rectifying currents are voltage-dependent, coupled to K(+) electrochemical gradient across the membrane, whereas the inward currents can be induced in response to activation of Ca(2+)-mobilizing receptors (PubMed:12754259, PubMed:15562060, PubMed:20871611, PubMed:22355750, PubMed:26919430, PubMed:30573346). Homo- and heterodimerizes to form functional channels with distinct regulatory and gating properties. In trigeminal ganglia sensory neurons, the heterodimers of KCNK18/TRESK and KCNK2/TREK-1 or KCNK10/TREK-2 inhibit neuronal firing and neurogenic inflammation by stabilizing the resting membrane potential at K(+) equilibrium potential as well as by regulating the threshold of action potentials and the spike frequency (By similarity). In thymocytes, conducts K(+) currents upon T cell receptor (TCR) signaling leading to sustained Ca(2+) influx and NF-kappa-B activation, FOXP3 transcription and positive selection of regulatory T cell (Treg) progenitor subsets (PubMed:34702947). Appears to mediate the analgesics effects of hydroxy-alpha-sanshool, a metabolite naturally present in Schezuan pepper and other Xanthoxylum plants (By similarity).
Involvement in disease
Migraine with or without aura 13
MGR13
A form of migraine transmitted in an autosomal dominant pattern. Migraine is a disabling symptom complex of periodic headaches, usually temporal and unilateral. Headaches are often accompanied by irritability, nausea, vomiting and photophobia, preceded by constriction of the cranial arteries. The two major subtypes are common migraine (migraine without aura) and classic migraine (migraine with aura). Classic migraine is characterized by recurrent attacks of reversible neurological symptoms (aura) that precede or accompany the headache. Aura may include a combination of sensory disturbances, such as blurred vision, hallucinations, vertigo, numbness and difficulty in concentrating and speaking.
None
The disease is caused by variants affecting the gene represented in this entry. Susceptibility to migraine has been shown to be conferred by a frameshift mutation that segregates with the disorder in a large multigenerational family. Migraine was associated with sensitivity to lights, sounds, and smells, as well as nausea and occasional vomiting. Triggers included fatigue, alcohol and bright lights. Mutations in KCNK18 are a rare cause of migraine.
Post-translational modifications
N-glycosylated.
Phosphorylation of Ser-264 is required for the binding of 14-3-3eta/YWHAH. Calcineurin-mediated dephosphorylation enhances channel activity.
Sequence Similarities
Belongs to the two pore domain potassium channel (TC 1.A.1.8) family.
Tissue Specificity
Expressed in dorsal root ganglion and trigeminal ganglion neurons. Detected at low levels in spinal cord. Expressed in regulatory T cells (at protein level).
Cellular localization
- Cell membrane
- Multi-pass membrane protein
Alternative names
TRESK, TRIK, KCNK18, Potassium channel subfamily K member 18, TWIK-related individual potassium channel, TWIK-related spinal cord potassium channel