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Compound
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Target Concepts:
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Query: UMLS:C0037315 (
sleep apnea
)
8,000
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
TWIK-related acid-sensitive
potassium
(TASK) channels-members of the two pore domain
potassium
(K
2P
) channel family-are found in neurons
1
, cardiomyocytes
2-4
and vascular smooth muscle cells
5
, where they are involved in the regulation of heart rate
6
, pulmonary artery tone
5,7
, sleep/wake cycles
8
and responses to volatile anaesthetics
8-11
. K
2P
channels regulate the resting membrane potential, providing background K
+
currents controlled by numerous physiological stimuli
12-15
. Unlike other K
2P
channels, TASK channels are able to bind inhibitors with high affinity, exceptional selectivity and very slow compound washout rates. As such, these channels are attractive drug targets, and TASK-1 inhibitors are currently in clinical trials for obstructive
sleep apnoea
and atrial fibrillation
16
. In general,
potassium
channels have an intramembrane vestibule with a selectivity filter situated above and a gate with four parallel helices located below; however, the K
2P
channels studied so far all lack a lower gate. Here we present the X-ray crystal structure of TASK-1, and show that it contains a lower gate-which we designate as an 'X-gate'-created by interaction of the two crossed C-terminal M4 transmembrane helices at the vestibule entrance. This structure is formed by six residues (
243
VLRFMT
248
) that are essential for responses to volatile anaesthetics
10
, neurotransmitters
13
and G-protein-coupled receptors
13
. Mutations within the X-gate and the surrounding regions markedly affect both the channel-open probability and the activation of the channel by anaesthetics. Structures of TASK-1 bound to two high-affinity inhibitors show that both compounds bind below the selectivity filter and are trapped in the vestibule by the X-gate, which explains their exceptionally low washout rates. The presence of the X-gate in TASK channels explains many aspects of their physiological and pharmacological behaviour, which will be beneficial for the future development and optimization of TASK modulators for the treatment of heart, lung and sleep disorders.
...
PMID:A lower X-gate in TASK channels traps inhibitors within the vestibule. 3249 42
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