Xenbase Image ID: 150258

Figure 1. SUR1 residues Q1342, I1347, and L1350 are essential for K-ATP channel activation by Diazoxide. (A) putative membrane topology of SUR1 (NBD, nucleotide-binding domain; WA, Walker A motif; WB, Walker B motif). The star indicates the region identified by Rainbow et al. (2004) and mutated to obtain the S1M chimera. (B) alignment of the amino acid sequences of human SUR1, rat SUR2A, and human MRP1. Three residues (boxed) are homologous in SURs and not in MRP1: Q1342, I1347, and L1350. Stars and squares indicate the MRP1 residues introduced in SUR1 to obtain SUR1S3M and SUR1S4M, respectively. (C) schematic representation of the chimeras. SUR1 and MRP1 elements are drawn in gray and black, respectively. For clarity, residues Q1342, I1347, and L1350 of SUR1 are indicated by white stripes. The amino acid composition of the constructs were as follows: SUR1S1M = SUR1(M1-V1313) + MRP1(V1261-F1341) + SUR1(R1394-K1582); SUR1S2M = SUR1(M1-P1336) + MRP1(P1284-L1300) + SUR1(V1352-K1582); SUR1S3M = SUR1 with mutations N1338S, I1345V, S1351C, and V1352L; SUR1S4M = SUR1 with mutations K1337S, D1341Q, K1344R, Q1346E, and Q1348R; SUR1(QIL/VFY) = SUR1 with mutations Q1342V, I1347F, and L1350Y, SUR1S2M(VFY/QIL) = SUR1S2M with mutations V1290Q, F1295I, and Y1298L. (D) Diazoxide responses were measured in inside-out patches excised from oocytes coexpressing Kir6.2 and wild type or chimeric SURs or MRP1 as indicated. Diazoxide (300 μmol/L) was applied in the presence of 100 μmol/L ATP, and currents were normalized to the current measured in the absence of nucleotides immediately before opener application. Application of 100 μmol/L ATP alone (black bars) was used as a control. Numbers at right of bars indicate the number of patches included in each average. (E) Representative patch-clamp recordings illustrating the responses of wild type and SUR1(QIL/VFY) channels to 300 μmol/L Diazoxide in the presence of 100 μmol/L ATP. SUR1, sulfonylurea receptor 1; MRP, multidrug-resistance associated protein. Image published in: Principalli MA et al. (2015) © 2015 The Authors. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View

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