ABCC8 p.Ser1448Ala
| Predicted by SNAP2: | A: N (93%), C: N (72%), D: N (97%), E: N (97%), F: N (66%), G: N (93%), H: N (93%), I: N (66%), K: N (93%), L: N (66%), M: N (82%), N: N (97%), P: N (93%), Q: N (97%), R: N (72%), T: N (97%), V: N (72%), W: N (53%), Y: N (72%), |
| Predicted by PROVEAN: | A: N, C: D, D: N, E: N, F: D, G: N, H: N, I: D, K: N, L: D, M: D, N: N, P: N, Q: N, R: N, T: N, V: D, W: D, Y: D, |
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[hide] Glucagon-like peptide-1 inhibits pancreatic ATP-se... Mol Endocrinol. 2002 Sep;16(9):2135-44. Light PE, Manning Fox JE, Riedel MJ, Wheeler MB
Glucagon-like peptide-1 inhibits pancreatic ATP-sensitive potassium channels via a protein kinase A- and ADP-dependent mechanism.
Mol Endocrinol. 2002 Sep;16(9):2135-44., [PMID:12198249]
Abstract [show]
Glucagon-like peptide-1 (GLP-1) elicits a glucose-dependent insulin secretory effect via elevation of cAMP and activation of protein kinase A (PKA). GLP-1-mediated closure of ATP-sensitive potassium (K(ATP)) channels is involved in this process, although the mechanism of action of PKA on the K(ATP) channels is not fully understood. K(ATP) channel currents and membrane potentials were measured from insulin-secreting INS-1 cells and recombinant beta-cell K(ATP) channels. 20 nM GLP-1 depolarized INS-1 cells significantly by 6.68 +/- 1.29 mV. GLP-1 reduced recombinant K(ATP) channel currents by 54.1 +/- 6.9% in mammalian cells coexpressing SUR1, Kir6.2, and GLP-1 receptor clones. In the presence of 0.2 mM ATP, the catalytic subunit of PKA (cPKA, 20 nM) had no effect on SUR1/Kir6.2 activity in inside-out patches. However, the stimulatory effects of 0.2 mM ADP on SUR1/Kir6.2 currents were reduced by 26.7 +/- 2.9% (P < 0.05) in the presence of cPKA. cPKA increased SUR1/Kir6.2 currents by 201.2 +/- 20.8% (P < 0.05) with 0.5 mM ADP present. The point mutation S1448A in the ADP-sensing region of SUR1 removed the modulatory effects of cPKA. Our results indicate that PKA-mediated phosphorylation of S1448 in the SUR1 subunit leads to K(ATP) channel closure via an ADP-dependent mechanism. The marked alteration of the PKA-mediated effects at different ADP levels may provide a cellular mechanism for the glucose-sensitivity of GLP-1.
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No. Sentence Comment
8 The point mutation S1448A in the ADP-sensing region of SUR1 removed the modulatory effects of cPKA.
X
ABCC8 p.Ser1448Ala 12198249:8:19
status: NEW87 We therefore generated a S1448A substitution mutant in the hamster SUR1 sequence and coexpressed this mutant with Kir6.2.
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ABCC8 p.Ser1448Ala 12198249:87:25
status: NEW88 Inside-out patch experiments revealed that the S1448A mutant was functionally expressed and possessed similar ATP and ADP-sensing properties when compared with WT SUR1/Kir6.2 channels (Fig. 5D).
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ABCC8 p.Ser1448Ala 12198249:88:47
status: NEW89 Under the identical conditions that produced a cPKA- induced significant reduction in WT KATP channel current (0.2 mM ATP and 0.2 mM ADP), SUR1(S1448A)/ Kir6.2 current was not significantly changed in the presence of 20 nM cPKA [95.40 Ϯ 2.8%, n ϭ 8 patches (P Ͼ 0.05), Fig. 5, A and C].
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ABCC8 p.Ser1448Ala 12198249:89:144
status: NEW99 cPKA, the SUR1(S1448A)/Kir6.2 current was also unaffected by application of cPKA (95.31 Ϯ 5.94, n ϭ 13 patches, Fig. 5B).
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ABCC8 p.Ser1448Ala 12198249:99:15
status: NEW146 The Effects of Purified PKA on Recombinant WT or KATP Channels Expressing the SUR1 Substitution Mutant, SUR1(S1448A) A and B, Representative recordings of Kir6.2/SUR1(S1448A) currents from excised inside-out membrane patches from tsA201 cells in response to application of 20 nM cPKA in the presence of either 0.2 mM ADP (A) or 0.5 mM ADP (B).
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ABCC8 p.Ser1448Ala 12198249:146:109
status: NEWX
ABCC8 p.Ser1448Ala 12198249:146:167
status: NEW148 C, Grouped data from WT (Kir6.2/ SUR1) or mutated (S1448A) KATP channels in response to application of cPKA, either in the presence or absence of ADP (0.2 mM) and ATP (0.2 mM) ATP continuously present.
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ABCC8 p.Ser1448Ala 12198249:148:51
status: NEW150 D, Grouped data, from inside-out patch experiments with WT and S1448A mutant KATP channels, showing a similar response to ATP alone (0.2 mM) and a release of this ATP-induced inhibition by ADP (0.2 mM).
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ABCC8 p.Ser1448Ala 12198249:150:63
status: NEW151 There were no statistical differences in nucleotide sensitivities between WT and S1448A KATP channels.
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ABCC8 p.Ser1448Ala 12198249:151:81
status: NEW196 Molecular Biology The S1448A point mutation was introduced into the hamster SUR1 clone, using the Unique Site Elimination (U.S.E.) Mutagenesis Kit as per the manufacturer`s instructions (Amersham Pharmacia Biotech, Piscataway, NJ) and confirmed by sequence analysis.
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ABCC8 p.Ser1448Ala 12198249:196:22
status: NEW