scholarly journals Estrogen ameliorates microglial activation by inhibiting the Kir2.1 inward-rectifier K+ channel

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Shih-Ying Wu ◽  
Yun-Wen Chen ◽  
Sheng-Feng Tsai ◽  
Sheng-Nan Wu ◽  
Yao-Hsiang Shih ◽  
...  
Keyword(s):  
Microglial Activation ◽  
Inward Rectifier ◽  
K Channel

scholarly journals Nucleotide inhibition of the pancreatic ATP-sensitive K+ channel explored with patch-clamp fluorometry

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Samuel G Usher ◽  
Frances M Ashcroft ◽  
Michael C Puljung
Keyword(s):  
Nucleotide Binding ◽  
Inward Rectifier ◽  
K Channel ◽  
Data Sets ◽  
Channel Activity ◽  
Unknown Mechanism ◽  
Apparent Affinity ◽  
Nucleotide Inhibition ◽  
Channel Currents ◽  
Combined Data

Pancreatic ATP-sensitive K+ channels (KATP) comprise four inward rectifier subunits (Kir6.2), each associated with a sulphonylurea receptor (SUR1). ATP/ADP binding to Kir6.2 shuts KATP. Mg-nucleotide binding to SUR1 stimulates KATP. In the absence of Mg2+, SUR1 increases the apparent affinity for nucleotide inhibition at Kir6.2 by an unknown mechanism. We simultaneously measured channel currents and nucleotide binding to Kir6.2. Fits to combined data sets suggest that KATP closes with only one nucleotide molecule bound. A Kir6.2 mutation (C166S) that increases channel activity did not affect nucleotide binding, but greatly perturbed the ability of bound nucleotide to inhibit KATP. Mutations at position K205 in SUR1 affected both nucleotide affinity and the ability of bound nucleotide to inhibit KATP. This suggests a dual role for SUR1 in KATP inhibition, both in directly contributing to nucleotide binding and in stabilising the nucleotide-bound closed state.

scholarly journals Functional expression of a vertebrate inwardly rectifying K+ channel in yeast.

1995 ◽  
Vol 6 (9) ◽  
pp. 1231-1240 ◽  
Author(s):  
W Tang ◽  
A Ruknudin ◽  
W P Yang ◽  
S Y Shaw ◽  
A Knickerbocker ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Xenopus Oocytes ◽  
Genetic System ◽  
Functional Expression ◽  
Inward Rectifier ◽  
K Channel ◽  
Coding Region ◽  
Low Potassium ◽  
K Current ◽  
Inwardly Rectifying

We describe the expression of gpIRK1, an inwardly rectifying K+ channel obtained from guinea pig cardiac cDNA. gpIRK1 is a homologue of the mouse IRK1 channel identified in macrophage cells. Expression of gpIRK1 in Xenopus oocytes produces inwardly rectifying K+ current, similar to the cardiac inward rectifier current IK1. This current is blocked by external Ba2+ and Cs+. Plasmids containing the gpIRK1 coding region under the transcriptional control of constitutive (PGK) or inducible (GAL) promoters were constructed for expression in Saccharomyces cerevisiae. Several observations suggest that gpIRK1 forms functional ion channels when expressed in yeast. gpIRK1 complements a trk1 delta trk2 delta strain, which is defective in potassium uptake. Expression of gpIRK1 in this mutant restores growth on low potassium media. Growth dependent on gpIRK1 is inhibited by external Cs+. The strain expressing gpIRK1 provides a versatile genetic system for studying the assembly and composition of inwardly rectifying K+ channels.

Comparative expression of the inward rectifier K+ channel GIRK2 in the cerebellum of normal and weaver mutant mice

1997 ◽  
Vol 753 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Inger Lauritzen ◽  
Jan De Weille ◽  
Christine Adelbrecht ◽  
Florian Lesage ◽  
Gustavo Murer ◽  
...  
Keyword(s):  
Inward Rectifier ◽  
Mutant Mice ◽  
K Channel

scholarly journals Codon Harmonization of a Kir3.1-KirBac1.3 Chimera for Structural Study Optimization

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 430
Author(s):  
Evan Van Aalst ◽  
Maryam Yekefallah ◽  
Anil K. Mehta ◽  
Isaac Eason ◽  
Benjamin Wylie
Keyword(s):  
Membrane Proteins ◽  
G Protein ◽  
Recombinant Expression ◽  
Protein Product ◽  
Inward Rectifier ◽  
Correlation Spectroscopy ◽  
Protein Yield ◽  
K Channel ◽  
Functional Assay ◽  
Nmr Studies

The expression of functional, folded, and isotopically enriched membrane proteins is an enduring bottleneck for nuclear magnetic resonance (NMR) studies. Indeed, historically, protein yield optimization has been insufficient to allow NMR analysis of many complex Eukaryotic membrane proteins. However, recent work has found that manipulation of plasmid codons improves the odds of successful NMR-friendly protein production. In the last decade, numerous studies showed that matching codon usage patterns in recombinant gene sequences to those in the native sequence is positively correlated with increased protein yield. This phenomenon, dubbed codon harmonization, may be a powerful tool in optimizing recombinant expression of difficult-to-produce membrane proteins for structural studies. Here, we apply this technique to an inward rectifier K+ Channel (Kir) 3.1-KirBac1.3 chimera. Kir3.1 falls within the G protein-coupled inward rectifier K+ (GIRK) channel family, thus NMR studies may inform on the nuances of GIRK gating action in the presence and absence of its G Protein, lipid, and small molecule ligands. In our hands, harmonized plasmids increase protein yield nearly two-fold compared to the traditional ‘fully codon optimized’ construct. We then employ a fluorescence-based functional assay and solid-state NMR correlation spectroscopy to show the final protein product is folded and functional.

Membrane potential oscillation from a novel combination of ion channels

1993 ◽  
Vol 265 (3) ◽  
pp. C720-C727 ◽  
Author(s):  
J. W. Stelling ◽  
T. J. Jacob
Keyword(s):  
Membrane Potential ◽  
Cell Voltage ◽  
Inward Rectifier ◽  
Constant Current ◽  
K Channel ◽  
Patch Clamp Recording ◽  
Current Clamp ◽  
Membrane Potential Oscillation ◽  
Low Amplitude

Single pigmented epithelial cells from the ciliary body of the eye were studied using the whole cell voltage and current clamp, permeabilized patch recording, and patch-clamp recording. These cells can produce two types of oscillation. Both are slow, with a period in the range of 1-2 min; one has a low amplitude and oscillates between -60 and -80 mV, and the second is larger, with biphasic hyperpolarizing and depolarizing phases. The latter was seen when the membrane potential was driven negative by a constant current and results from the interplay between the inward rectifier K+ channel and a hyperpolarizing-activated cation channel. The hyperpolarization is caused by the constant current acting on a decreasing conductance as the inward rectifier inactivates, and the depolarization drive results from the activation of cation channels. It is suggested that the constant current would be provided by the Na+ pump in vivo, and such an interplay of channels and pumps could drive the uptake of cations in absorbing epithelia or provide an increased driving force for chloride exit in secretory epithelia.

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