ABCC8 p.Ala161Cys
| Predicted by SNAP2: | C: N (82%), D: N (87%), E: N (78%), F: N (82%), G: N (93%), H: N (87%), I: N (87%), K: N (82%), L: N (87%), M: N (87%), N: N (93%), P: N (87%), Q: N (93%), R: N (87%), S: N (97%), T: N (93%), V: N (93%), W: D (59%), Y: N (82%), |
| Predicted by PROVEAN: | C: N, D: N, E: N, F: D, G: N, H: N, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: D, Y: N, |
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[hide] The kinetic and physical basis of K(ATP) channel g... Biophys J. 2000 May;78(5):2334-48. Enkvetchakul D, Loussouarn G, Makhina E, Shyng SL, Nichols CG
The kinetic and physical basis of K(ATP) channel gating: toward a unified molecular understanding.
Biophys J. 2000 May;78(5):2334-48., [PMID:10777731]
Abstract [show]
K(ATP) channels can be formed from Kir6.2 subunits with or without SUR1. The open-state stability of K(ATP) channels can be increased or reduced by mutations throughout the Kir6.2 subunit, and is increased by application of PIP(2) to the cytoplasmic membrane. Increase of open-state stability is manifested as an increase in the channel open probability in the absence of ATP (Po(zero)) and a correlated decrease in sensitivity to inhibition by ATP. Single channel lifetime analyses were performed on wild-type and I154C mutant channels expressed with, and without, SUR1. Channel kinetics include a single, invariant, open duration; an invariant, brief, closed duration; and longer closed events consisting of a "mixture of exponentials," which are prolonged in ATP and shortened after PIP(2) treatment. The steady-state and kinetic data cannot be accounted for by assuming that ATP binds to the channel and causes a gate to close. Rather, we show that they can be explained by models that assume the following regarding the gating behavior: 1) the channel undergoes ATP-insensitive transitions from the open state to a short closed state (C(f)) and to a longer-lived closed state (C(0)); 2) the C(0) state is destabilized in the presence of SUR1; and 3) ATP can access this C(0) state, stabilizing it and thereby inhibiting macroscopic currents. The effect of PIP(2) and mutations that stabilize the open state is then to shift the equilibrium of the "critical transition" from the open state to the ATP-accessible C(0) state toward the O state, reducing accessibility of the C(0) state, and hence reducing ATP sensitivity.
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No. Sentence Comment
51 Patches were exposed to differing [ATP] as indicated Table 1 K1/2,ATP and Pozero values (estimated from noise analysis or single channels) for mutant Kir6.2 ؉ SUR1 channels examined in this study (L164, R176 mutants), in Shyng et al. (1997a, N160 mutants) and in Loussouarn et al. (2000, Cysteine substitutions) Pozero Ϯ SE mean K1/2,ATP (M) Ϯ SE WT 0.45 Ϯ 0.09 12 Ϯ 1.6 L164T 0.89 Ϯ 0.01 4,300 L164G 0.89 Ϯ 0.03 3,600 L164A 0.87 Ϯ 0.02 520 L164V 0.78 Ϯ 0.04 7 R176A 0.01 Ϯ 0.001 5 N160D 0.83 Ϯ 0.01 46 N160A 0.76 Ϯ 0.02 6 N160E 0.83 Ϯ 0.03 18 Ctrl 0.88 Ϯ 0.02 1,060 Ϯ 10 Ctrl N/D 0.88 Ϯ 0.01 1,060 Ϯ 24 Ctrl-N153C 0.88 Ϯ 0.02 230 Ϯ 76 Ctrl-I154C 0.89 Ϯ 0.01 330 Ϯ 30 Ctrl-L157C N/D 0.89 Ϯ 0.01 420 Ϯ 270 Ctrl-M158C N/D 0.89 Ϯ 0.02 4,200 Ϯ 1300 Ctrl-A161C N/D 0.88 Ϯ 0.01 110 Ϯ 8 Ctrl-I162C N/D 0.86 Ϯ 0.03 33 Ϯ 6 Ctrl-M163C N/D 0.90 Ϯ 0.02 190 Ϯ 54 Ctrl-L164C N/D 0.89 Ϯ 0.01 Ͼ100,000 Ctrl-I167C N/D 0.88 Ϯ 0.02 1,100 Ϯ 250 Ctrl-M169C N/D 0.90 Ϯ 0.01 110 Ϯ 17 Ctrl-T171C 0.91 Ϯ 0.02 2,800 Ϯ 820 Ctrl-Q173C 0.88 Ϯ 0.01 33 Ϯ 4 Ctrl-H175C N/D 0.90 Ϯ 0.03 24,500 Ϯ 4970 All channels were coexpressed with SUR1 subunits.
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ABCC8 p.Ala161Cys 10777731:51:908
status: NEW[hide] Transmembrane topology of the sulfonylurea recepto... J Biol Chem. 2001 Nov 2;276(44):41270-8. Epub 2001 Aug 23. Conti LR, Radeke CM, Shyng SL, Vandenberg CA
Transmembrane topology of the sulfonylurea receptor SUR1.
J Biol Chem. 2001 Nov 2;276(44):41270-8. Epub 2001 Aug 23., [PMID:11546780]
Abstract [show]
Sulfonylurea receptors (SURx) are multi-spanning transmembrane proteins of the ATP-binding cassette (ABC) family, which associate with Kir6.x to form ATP-sensitive potassium channels. Two models, with 13-17 transmembrane segments, have been proposed for SURx topologies. Recently, we demonstrated that the amino-terminal region of SUR1 contains 5 transmembrane segments, supporting the 17-transmembrane model. To investigate the topology of the complete full-length SUR1, two strategies were employed. Topology was probed by accessibility of introduced cysteines to a membrane-impermeable biotinylating reagent, biotin maleimide. Amino acid positions 6/26, 99, 159, 337, 567, 1051, and 1274 were accessible, therefore extracellular, whereas many endogenous and some introduced cysteines were inaccessible, thus likely cytoplasmic or intramembrane. These sites correspond to extracellular loops 1-3, 5-6, and 8 and the NH2 terminus, and intracellular loops 3-8 and COOH terminus in the 17-transmembrane model. Immunofluorescence was used to determine accessibility of epitope-tagged SUR1 in intact and permeabilized cells. Epitopes at positions 337 and 1050 (putative external loops 3 and 6) were labeled in intact cells, therefore external, whereas positions 485 and 1119 (putative internal loops 5 and 7) only were accessible after permeabilization and therefore internal. These results are compatible with the 17-transmembrane model with two pairs of transmembrane segments as possible reentrant loops.
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No. Sentence Comment
166 Several of the mutations (A161C, R388C, P1162C, and R1300C) produced SUR1 proteins that did not show a complex glycosylated form, and these were not evaluated further.
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ABCC8 p.Ala161Cys 11546780:166:26
status: NEW165 Several of the mutations (A161C, R388C, P1162C, and R1300C) produced SUR1 proteins that did not show a complex glycosylated form, and these were not evaluated further.
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ABCC8 p.Ala161Cys 11546780:165:26
status: NEW