Identification of molecular regions responsible for the membrane trafficking of Kir6.2

The subunits of the pancreatic ATP-sensitive potassium channel Kir6.2 and the sulphonylurea receptor (SUR1) contain endoplasmic reticulum (ER) retention signals (RKR), which prevent their plasma membrane expression when expressed individually. When co-expressed, however, these signals are masked and...

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Bibliographic Details
Published in:Pflügers Archiv 2000-07, Vol.440 (3), p.481-487
Main Authors: Hough, E, Beech, D J, Sivaprasadarao, A
Format: Article
Language:English
Subjects:
Animals
Biological Transport - genetics
Cell Membrane - chemistry
Cell Membrane - metabolism
Cloning, Molecular
COS Cells
Electrophysiology
Epitopes - chemistry
Epitopes - genetics
Epitopes - metabolism
Gene Expression - physiology
Glyburide - metabolism
Glyburide - pharmacology
Hypoglycemic Agents - metabolism
Hypoglycemic Agents - pharmacology
Membrane Potentials - physiology
Mice
Oocytes - physiology
Pancreas - chemistry
Pancreas - metabolism
Patch-Clamp Techniques
Potassium Channels - chemistry
Potassium Channels - genetics
Potassium Channels - metabolism
Potassium Channels, Inwardly Rectifying
Protein Structure, Tertiary
Proteins
Recombinant Fusion Proteins - chemistry
Recombinant Fusion Proteins - genetics
Recombinant Fusion Proteins - metabolism
Transfection
Tritium
Xenopus
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Summary:The subunits of the pancreatic ATP-sensitive potassium channel Kir6.2 and the sulphonylurea receptor (SUR1) contain endoplasmic reticulum (ER) retention signals (RKR), which prevent their plasma membrane expression when expressed individually. When co-expressed, however, these signals are masked and the complex traffics to the plasma membrane. To investigate this further, we have expressed epitope-tagged chimaeras between Kir6.2 and Kir2.1 (which traffics to the membrane independently of SUR1) in Xenopus oocytes alone and together with SUR1. By staining sections of the oocytes, we show that, in addition to the ER retention signal present in the distal C-terminus, the M2 transmembrane and the proximal C-terminal regions also contribute to the inability of Kir6.2 to traffic to the membrane in the absence of SUR1. Furthermore, by staining the whole oocytes for the hexa-histidine tag attached to the N-terminus of SUR1, we provide direct experimental evidence that the N-terminus of SUR1 is extracellular.
ISSN:0031-6768
1432-2013
DOI:10.1007/s004240000311