Inward rectifiers and their regulation by endogenous polyamines

Baronas, Victoria A.; Kurata, Harley T.

doi:10.3389/fphys.2014.00325

Cited by 62 publications

(52 citation statements)

References 121 publications

(244 reference statements)

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“…This effect is concentration-dependent and correlated with stomatal closure. They also inhibit the inwardrectifying and outward-rectifying K + channels in root cells [6,58].…”

Section: Signaling Components Providing Linkage Between Polyamines Anmentioning

confidence: 99%

“…Both H 2 O 2 and hydroxyl radicals mediate multiple ion channels, including those responsible for Ca + influx and K + efflux [6,58]. In addition, polyamine-induced NO generation also causes the inhibition of outwardrectifying K + channels by direct nitrosylation, and the activation of plasma membrane H + -ATP-ase [6].…”

Section: Signaling Components Providing Linkage Between Polyamines Anmentioning

confidence: 99%

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Speculation: Polyamines are important in abiotic stress signaling

2015

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The main role of polyamines was originally assumed to be as direct protective compounds important under stress conditions. Although in some cases a correlation was found between the endogenous polyamine content and stress tolerance, this relationship cannot be generalized. Polyamines should no longer be considered simply as protective molecules, but rather as compounds that are involved in a complex signaling system and have a key role in the regulation of stress tolerance. The major links in polyamine signaling may be H 2 O 2 and NO, which are not only produced in the course of the polyamine metabolism, but also transmit signals that influence gene expression via an increase in the cytoplasmic Ca 2+ level.Polyamines can also influence Ca 2+ influx independently of the H 2 O 2 -and/or NO-mediated pathways. Furthermore, these pathways may converge. In addition, several protein kinases have been shown to be influenced at the transcriptional or post-translational level by polyamines. Individual polyamines can be converted into each other in the polyamine cycle.In addition, their metabolism is linked with other hormones or signaling molecules. However, as individual polyamines trigger different transcriptional responses, other mechanisms and the existence of polyamine-responsive elements and the corresponding transacting protein factors are also involved in polyamine-related signaling pathways. Highlights:-Polyamines are interconvertible in the polyamine cycle -The statement "the higher the polyamine level the better" cannot be generalized -In stress responses the ratio of signaling to direct protection is more important -Polyamines are also involved in hormonal cross-talk -H 2 O 2 and NO are the major but not the only links in polyamine stress signaling

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“…This effect is concentration-dependent and correlated with stomatal closure. They also inhibit the inwardrectifying and outward-rectifying K + channels in root cells [6,58].…”

Section: Signaling Components Providing Linkage Between Polyamines Anmentioning

confidence: 99%

Section: Signaling Components Providing Linkage Between Polyamines Anmentioning

confidence: 99%

Speculation: Polyamines are important in abiotic stress signaling

2015

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“…For almost all ion channels, cytoplasmic polyamine block is observed at negative and physiologically relevant membrane potentials, making it an ideal regulator of cellular excitability (Nichols & Lopatin, ; Bowie et al . ; Lu, ; Baronas & Kurata, ). In contrast, polyamine permeation occurs at extreme (>+50 mV) positive membrane potentials (Bahring et al .…”

Section: Introductionmentioning

confidence: 99%

Kainate receptor pore‐forming and auxiliary subunits regulate channel block by a novel mechanism

Brown

Aurousseau

Musgaard

et al. 2016

The Journal of Physiology

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Key points Kainate receptor heteromerization and auxiliary subunits, Neto1 and Neto2, attenuate polyamine ion‐channel block by facilitating blocker permeation.Relief of polyamine block in GluK2/GluK5 heteromers results from a key proline residue that produces architectural changes in the channel pore α‐helical region.Auxiliary subunits exert an additive effect to heteromerization, and thus relief of polyamine block is due to a different mechanism.Our findings have broad implications for work on polyamine block of other cation‐selective ion channels. AbstractChannel block and permeation by cytoplasmic polyamines is a common feature of many cation‐selective ion channels. Although the channel block mechanism has been studied extensively, polyamine permeation has been considered less significant as it occurs at extreme positive membrane potentials. Here, we show that kainate receptor (KAR) heteromerization and association with auxiliary proteins, Neto1 and Neto2, attenuate polyamine block by enhancing blocker permeation. Consequently, polyamine permeation and unblock occur at more negative and physiologically relevant membrane potentials. In GluK2/GluK5 heteromers, enhanced permeation is due to a single proline residue in GluK5 that alters the dynamics of the α‐helical region of the selectivity filter. The effect of auxiliary proteins is additive, and therefore the structural basis of polyamine permeation and unblock is through a different mechanism. As native receptors are thought to assemble as heteromers in complex with auxiliary proteins, our data identify an unappreciated impact of polyamine permeation in shaping the signalling properties of neuronal KARs and point to a structural mechanism that may be shared amongst other cation‐selective ion channels.

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“…In Kir channels inward rectification is generated by a voltage dependent block by cytosolic Mg 2+ or polyamines (Baronas and Kurata, 2014;Nichols and Lee, 2018). The finding that Kmpv SP1 rectifies in a bath solution with only KCl and HEPES in the same manner as in cells suggests that the channel may harbor an inherent mechanism of rectification.…”

Section: The Inward Rectification Is An Inherent Function Of Kmpv Sp1mentioning

confidence: 99%

A small viral potassium ion channel with an inherent inward rectification

Eckert

Schulze

Stahl

et al. 2019

Preprint

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Some algal viruses have coding sequences for K + channels with structural and functional characteristics of pore modules of complex K + channels. Here we exploit the immense structural diversity of natural channel orthologs to discover new basic principles of structure/function correlates in K + channels. The comparative analysis of three similar K + channels with monomer sizes ≤ 86 amino acids (AA) shows that one channel (Kmpv 1 ) generates an ohmic conductance in HEK293 cells while the other two channels (Kmpv SP1 , Kmpv PL1 ) exhibit typical features of canonical Kir channels. Like Kir channels, the rectification of the viral channels is a function of the K + driving force. Reconstitution of Kmpv SP1 and Kmpv PL1 in planar lipid bilayers showed rapid channel fluctuations only at voltages negative of the K + reversal voltage. This rectification was maintained in KCl buffer with 1 mM EDTA, which excludes blocking cations as the source of rectification. This means that rectification of the viral channels must be, unlike Kir channels, an inherent property of the channel proteins. The structural basis for rectification was investigated by a chimera between rectifying and non-rectifying channels as well as point mutations, which made the rectifying channels similar to the ohmic conducting channel. The results of these experiments exclude the domain, which connects the two transmembrane helixes and which includes the pore helix and the selectivity filter, as playing a major role in rectification; inward rectification must be conferred by the transmembrane domains. The finding that a swapping of the AA, which is typical for the two inward rectifiers, with the respective AA from Kmpv 1 did not compromise rectification suggests that tertiary or quaternary structural interactions are responsible for this type of gating.

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Inward rectifiers and their regulation by endogenous polyamines

Cited by 62 publications

References 121 publications

Speculation: Polyamines are important in abiotic stress signaling

Speculation: Polyamines are important in abiotic stress signaling

Kainate receptor pore‐forming and auxiliary subunits regulate channel block by a novel mechanism

A small viral potassium ion channel with an inherent inward rectification

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