Hyperpolarization-activated chloride currents in Xenopus oocytes.

Kowdley, Gopal C.; Ackerman, Stephen J.; John, J. Edward; Jones, Larry R.; Moorman, J. Randall

doi:10.1085/jgp.103.2.217

Cited by 91 publications

(65 citation statements)

References 39 publications

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“…Permeability of cations other than K+ through the DelS1-S4 channel has been confirmed in our single channel experiments with sodium aspartate as charge carrier. The possibility that the current through the DelS1-S4 channel is carried by Clions, like the hyperpolarization-activated Cl-current described by Kowdley, Ackerman, John, Jones & Moorman (1994), can be excluded based on the following observations: (i) Vrev became more negative as [KCl]. was decreased (Fig.…”

Section: Discussionmentioning

confidence: 99%

Reversal of rectification and alteration of selectivity and pharmacology in a mammalian Kv1.1 potassium channel by deletion of domains S1 to S4.

Tytgat

Vereecke

Carmeliet

1994

The Journal of Physiology

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1. A possible relation between the family of inwardly rectifying K+ channels and the Shaker superfamily of K+ channels was investigated using a deletion mutant (DelS1-S4) of a delayed rectifier Kvl.1 (RCK1) K+ channel. (Ho et al. 1993), and GIRKI (Kubo, Reuveny, Slesinger, Jan & Jan, 1993b), is structurally analogous to the inner core of the Shaker superfamily of K+ channels with six transmembranespanning regions (SI to S6) (Kubo et al. 1993a;Nichols, 1993). According to this model, the lining of the pore in classic inward rectifiers is formed by the H5 domain flanked by transmembrane domains MI and M2, whereas the inner core in Shaker-type channels is formed by the analogous domains H5, S5 and S6. If the structures of the two families of K+ channels are indeed analogous, it is feasible that inwardly rectifying K+ channels also have a tetrameric stoichiometry (MacKinnon, 1991;Liman, Tytgat & Hess, 1992;Nichols, 1993). To investigate a possible structural and evolutionary relation between these two families of channels, we constructed a deletion mutant (DelSi-S4) of a delayed rectifier Kv1.1 (RCKI) K+ channel lacking the entire sequence coding for transmembrane domains SI to S4 with re-ligation of the aminoterminal domain to transmembrane domain S5. In order to elucidate also the stoichiometry of inwardly rectifying K+ channels, we conserved the Shaker Ti tetramerization domain present in the cytoplasmic amino terminus.

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Section: Discussionmentioning

confidence: 99%

Reversal of rectification and alteration of selectivity and pharmacology in a mammalian Kv1.1 potassium channel by deletion of domains S1 to S4.

Tytgat

Vereecke

Carmeliet

1994

The Journal of Physiology

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“…Although an accurate measure of the kinetics of HCN channel activation in the presence of TRIP8b could not be obtained [because of the small size of the residual I h and the confounding effect of the endogenous chloride currents of the oocytes (Kowdley et al, 1994)], we did not observe any effect of TRIP8b on the voltage dependence of HCN channel activation, suggesting a limited effect on the biophysical properties of the channels (in cell-attached patch recordings, V 1/2 for HCN2 plus GFP was Ϫ120 Ϯ 6 mV, n ϭ 10; V 1/2 for HCN2 plus TRIP8b was Ϫ124 Ϯ 6 mV, n ϭ 10; mean Ϯ SD; t test; p Ͼ 0.05). Thus, we proceeded to examine whether TRIP8b altered surface expression of HCN channels.…”

Section: Trip8b Alters the Intracellular Trafficking Of Hcn Channelsmentioning

confidence: 99%

Regulation of HCN Channel Surface Expression by a Novel C-Terminal Protein-Protein Interaction

Santoro

Wainger²,

Siegelbaum³

2004

J. Neurosci.

190

239

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Hyperpolarization-activated cation currents (I h ) are carried by channels encoded by a family of four genes (HCN1-4) that are differentially expressed within the brain in specific cellular and subcellular compartments. HCN1 shows a high level of expression in apical dendrites of cortical pyramidal neurons and in presynaptic terminals of cerebellar basket cells, structures with a high density of I h . Expression of I h is also regulated by neuronal activity. To isolate proteins that may control HCN channel expression or function, we performed yeast two-hybrid screens using the C-terminal cytoplasmic tails of the HCN proteins as bait. We identified a brain-specific protein, which has been previously termed TRIP8b (for TPR-containing Rab8b interacting protein) and PEX5Rp (for Pex5p-related protein), that specifically interacts with all four HCN channels through a conserved sequence in their C-terminal tails. In situ hybridization and immunohistochemistry show that TRIP8b and HCN1 are colocalized, particularly within dendritic arbors of hippocampal CA1 and neocortical layer V pyramidal neurons. The dendritic expression of TRIP8b in layer V pyramidal neurons is disrupted after deletion of HCN1 through homologous recombination, demonstrating a key in vivo interaction between HCN1 and TRIP8b. TRIP8b dramatically alters the trafficking of HCN channels heterologously expressed in Xenopus oocytes and human embryonic kidney 293 cells, causing a specific decrease in surface expression of HCN protein and I h density, with a pronounced intracellular accumulation of HCN protein that is colocalized in discrete cytoplasmic clusters with TRIP8b. Finally, TRIP8b expression in cultured pyramidal neurons markedly decreases native I h density. These data suggest a possible role for TRIP8b in regulating HCN channel density in the plasma membrane.

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“…Injecting large amounts of cDNA, in contrast, yielded anion currents with an iodide > chloride conductivity sequence which activated slowly upon strong hyperpolarization (in excess of-100 mV) (data not shown). However, similar currents are endogenous to Xenopus oocytes [25] and can also be provoked by overexpression of phospholemman [26], Mat-8 [27], minK (also named IsK [28]) [29] and mutants of C1C-1 which are closed in that voltagerange [19]. Thus, it seems that these currents are just an artifact of overexpressing membrane proteins in Xenopus oocytes [30].…”

Section: Clc-6 Clc-7mentioning

confidence: 99%

ClC‐6 and ClC‐7 are two novel broadly expressed members of the CLC chloride channel family

1995

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We cloned two novel members of the CLC chloride channel family from rat and human brain. CIC-6 is a 97-kDa protein, and CIC-7 a 89-kDa protein roughly 45% identical with CIC-6. Together they define a new branch of this gene family. Both genes are very broadly expressed, e.g. in brain, testes, muscle and kidney. In mouse embryos, both genes are expressed as early as day 7. While the human gene for CIC-6 is located on human chromosome lp36 and shares this region with hCIC-Ka and hCIC-Kb, CIC-7 is on 16p13. CIC-6 has a highly conserved glycosylation site between transmembrane domains D8 and D9, while CIC-7 is the only known eukaryotic CIC protein which lacks this site. Hydropathy analysis indicates that domain D4 cannot serve as a transmembrane domain. Both CIC-6 and CIC-7 cannot be expressed as chloride channels in Xenopus oocytes, either singly or in combination.

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Hyperpolarization-activated chloride currents in Xenopus oocytes.

Cited by 91 publications

References 39 publications

Reversal of rectification and alteration of selectivity and pharmacology in a mammalian Kv1.1 potassium channel by deletion of domains S1 to S4.

Reversal of rectification and alteration of selectivity and pharmacology in a mammalian Kv1.1 potassium channel by deletion of domains S1 to S4.

Regulation of HCN Channel Surface Expression by a Novel C-Terminal Protein-Protein Interaction

ClC‐6 and ClC‐7 are two novel broadly expressed members of the CLC chloride channel family

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