ABCMdb

ABCC8 p.Met1289Leu

Predicted by SNAP2:	A: D (59%), C: D (75%), D: D (75%), E: D (63%), F: D (71%), G: D (71%), H: D (80%), I: D (66%), K: D (66%), L: D (66%), N: D (59%), P: D (85%), Q: N (66%), R: D (63%), S: N (53%), T: D (53%), V: D (63%), W: D (85%), Y: D (75%),
Predicted by PROVEAN:	A: N, C: N, D: N, E: N, F: N, G: N, H: N, I: N, K: N, L: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: N, Y: N,

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Publications
[hide] Effect of two amino acids in TM17 of Sulfonylurea ... Diabetes. 2004 Dec;53 Suppl 3:S128-34. Hambrock A, Kayar T, Stumpp D, Osswald H
Effect of two amino acids in TM17 of Sulfonylurea receptor SUR1 on the binding of ATP-sensitive K+ channel modulators.
Diabetes. 2004 Dec;53 Suppl 3:S128-34., [PMID:15561900]

Abstract [show]
The sulfonylurea receptor (SUR) is the important regulatory subunit of ATP-sensitive K+ channels. It is an ATP-binding cassette protein comprising 17 transmembrane helices. SUR is endowed with binding sites for channel blockers like the antidiabetic sulfonylurea glibenclamide and for the chemically very heterogeneous channel openers. SUR1, the typical pancreatic SUR isoform, shows much higher affinity for glibenclamide but considerably lower affinity for most openers than SUR2. In radioligand binding assays, we investigated the role of two amino acids, T1285 and M1289, located in transmembrane helix (TM)-17, in opener binding to SUR1. These amino acids were exchanged for the corresponding amino acids of SUR2. In competition experiments using [3H]glibenclamide as radioligand, SUR1(T1285L, M1289T) showed much higher affinity toward the cyanoguanidine openers pinacidil and P1075 than SUR1 wild type. The affinity for the thioformamide aprikalim was also markedly increased. In contrast, the affinity for the benzopyrans rilmakalim and levcromakalim was unaffected; however, the amount of displaced [3H]glibenclamide binding was nearly doubled. The binding properties of the opener diazoxide and the blocker glibenclamide were unchanged. In conclusion, mutation of two amino acids in TM17 of SUR1, especially of M1289, leads to class-specific effects on opener binding by increasing opener affinity or by changing allosteric coupling between opener and glibenclamide binding.

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No. Sentence Comment
96 As we intended to compare binding properties of SUR1 with the mutants SUR1(T1285L, M1289L) and SUR1(M1289L), [3 H]glibenclamide was chosen as the radioligand due to its high affinity to SUR1. Login to comment
100 Displacing [3 H]glibenclamide by increasing concentrations of unlabeled glibenclamide (Fig. 2A) resulted in similar monophasic inhibition curves for SUR1, SUR1 (M1289L), and SUR1(T1285L, M1289L) with KD values of thioformamide: aprikalim [F]; and benzothiadiazine: diazoxide [G]. Login to comment
111 Glibenclamide binding was not significantly changed by the mutations [pKi SUR1 (M1289L) vs. SUR1: P ϭ 0.0868; pKi SUR1(T1285L, M1289L) vs. SUR1: P ϭ 0.0825]. Login to comment
112 In the following experiments, binding of openers representative of different chemical classes was systematically compared between SUR1 and SUR1(T1285L, M1289L); for P1075, levcromakalim, and diazoxide, the mutant SUR1 (M1289L) was also investigated. Login to comment
118 Binding of P1075 to SUR1(T1285L, M1289T) did not differ much from binding to SUR1(M1289L) (Table 1). Login to comment