J. Neurophysiol. 86, 130-142 (2001)[PubMed:11431495]
We report the cloning of human KT3.2 and KT3.3 new members of the two-pore K(+) channel (KT) family. Based on amino acid sequence and phylogenetic analysis, KT3.2, KT3.3, and TASK-1 constitute a subfamily within the KT channel mammalian family. When Xenopus oocytes were injected with KT3.2 cRNA, the resting membrane potential was brought close to the potassium equilibrium potential. At low extracellular K(+) concentrations, two-electrode voltage-clamp recordings revealed the expression of predominantly outward currents. With high extracellular K(+) (98 mM), the current-voltage relationship exhibited weak outward rectification. Measurement of reversal potentials at different [K(+)](o) revealed a slope of 48 mV per 10-fold change in K(+) concentration as expected for a K(+)-selective channel. Unlike TASK-1, which is highly sensitive to changes of pH in the physiological range, KT3.2 currents were relatively insensitive to changes in intracellular or extracellular pH within this range due to a shift in the pH dependency of KT3.2 of 1 pH unit in the acidic direction. On the other hand, the phorbol ester phorbol 12-myristate 13-acetate (PMA), which does not affect TASK-1, produces strong inhibition of KT3.2 currents. Human KT3.2 mRNA expression was most prevalent in the cerebellum. In rat, KT3.2 is exclusively expressed in the brain, but it has a wide distribution within this organ. High levels of expression were found in the cerebellum, medulla, and thalamic nuclei. The hippocampus has a nonhomogeneous distribution, expressing at highest levels in the lateral posterior and inferior portions. Medium expression levels were found in neocortex. The KT3.2 gene is located at chromosome 8q24 1-3, and the KT3.3 gene maps to chromosome 20q13.1.
We have isolated, by degenerate PCR, a complementary DNA encoding a novel two pore domain potassium channel. This is the 7th functional member of the human tandem pore domain potassium channel family to be reported. It has an open reading frame of 1.125 kb and encodes a 374 amino acid protein which shows 62% identity to the human TASK-1 gene: identity to other human members of the family is 31-35% at the amino acid level. We believe this gene to be human TASK-3, the ortholog of the recently reported rat TASK-3 gene: amino acid identity between the two is 74%. 'Taqman' mRNA analysis demonstrated a very specific tissue distribution pattern, showing human TASK-3 mRNA to be localised largely in the cerebellum, in contrast rat TASK-3 was reported to be widely distributed. We have shown by radiation hybrid mapping that human TASK-3 can be assigned to chromosome 8q24.3. Human TASK-3 was demonstrated to endow Xenopus oocytes with a negative resting membrane potential through the presence of a large K(+) selective conductance. TASK-3 is inhibited by extracellular acidosis with a mid-point of inhibition around pH 6. 5, supporting the predictions from the sequence data that this is a third human TASK (TWIK-related acid sensitive K(+) channel) gene.
Catalysis of facilitated diffusion of a potassium ion (by an energy-independent process) involving passage through a transmembrane aqueous pore or channel without evidence for a carrier-mediated mechanism.
Catalysis of the transmembrane transfer of an ion by a voltage-gated channel. An ion is an atom or group of atoms carrying an electric charge by virtue of having gained or lost one or more electrons. A voltage-gated channel is a channel whose open state is dependent on the voltage across the membrane in which it is embedded.
The progression of the cochlea over time from its formation to the mature structure. The cochlea is the snail-shaped portion of the inner ear that is responsible for the detection of sound.
We have isolated, by degenerate PCR, a complementary DNA encoding a novel two pore domain potassium channel. This is the 7th functional member of the human tandem pore domain potassium channel family to be reported. It has an open reading frame of 1.125 kb and encodes a 374 amino acid protein which shows 62% identity to the human TASK-1 gene: identity to other human members of the family is 31-35% at the amino acid level. We believe this gene to be human TASK-3, the ortholog of the recently reported rat TASK-3 gene: amino acid identity between the two is 74%. 'Taqman' mRNA analysis demonstrated a very specific tissue distribution pattern, showing human TASK-3 mRNA to be localised largely in the cerebellum, in contrast rat TASK-3 was reported to be widely distributed. We have shown by radiation hybrid mapping that human TASK-3 can be assigned to chromosome 8q24.3. Human TASK-3 was demonstrated to endow Xenopus oocytes with a negative resting membrane potential through the presence of a large K(+) selective conductance. TASK-3 is inhibited by extracellular acidosis with a mid-point of inhibition around pH 6. 5, supporting the predictions from the sequence data that this is a third human TASK (TWIK-related acid sensitive K(+) channel) gene.
Inhibited by phorbol 12-myristate 13-acetate (PMA). TASK-3 current is strongly decreased in the presence of an extracellular pH inferior to 7.0.
CuratedUniProtKB
Overexpressed in a high proportion of breast cancers. May confer resistance to growth factor deprivation and hypoxia, thereby promoting tumor cell survival in poorly oxygenated areas of solid tumors.
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
Protein which is part of a transmembrane protein complex that forms a hydrophilic channel across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradients. The channels are usually gated and only open in response to a specific stimulus, such as a change in membrane potential (voltage-gated) or the binding of a ligand (ligand-gated channel).
Protein which is part of a transmembrane protein complex that forms a hydrophilic channel across the lipid bilayer through which potassium ions can diffuse down their electrochemical gradient. The channels are gated and only open in response to a specific stimulus, such as a change in membrane potential (voltage-gated). They are important for the regulation of the resting membrane potential and for the control of the shape and frequency of action potentials.
Protein which is a component of a voltage-gated channel. Voltage-gated ion channels are responsible for the electrical activity in a variety of cell types. They probably exist in all life forms.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
My favorites 
My labels 
Login
