Voltage gating and permeation in a gap junction hemichannel.

Trexler, E. Brady; Bennett, Michael V. L.; Bargiello, Thaddeus A.; Verselis, Vytas K.

doi:10.1073/pnas.93.12.5836

Cited by 294 publications

(413 citation statements)

References 18 publications

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“…Note that zebrafish Cx43 does not exhibit hemichannel activity [15], and is therefore not an appropriate positive control. Connexin hemichannels have been shown to take-up dye from the extracellular medium under conditions of low extracellular calcium and mechanical stimulation [14,[17][18][19][20][21]. Under these conditions and in the presence of sulfo-rhodamine, we found significant hemichannel activity of both human Cx43-EGFP and untagged Cx23a when compared to cells transfected with EGFP alone (Fig.…”

Section: Cx23a Forms Functional Hemichannelsmentioning

confidence: 79%

Cx23, a connexin with only four extracellular‐loop cysteines, forms functional gap junction channels and hemichannels

et al. 2007

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Gap junction channels may be comprised of either connexin or pannexin proteins (innexins and pannexins). Membrane topologies of both families are similar, but sequence similarity is lacking. Recently, connexin-like sequences have been identified in mammalian and zebrafish genomes that have only four conserved cysteines in the extracellular domains (Cx23), a feature of the pannexins. Phylogenetic analyses of the noncanonical ''C4'' connexins reveal that these sequences are indeed connexins. Functional assays reveal that the Cx23 gap junctions are capable of sharing neurobiotin, and further, that Cx23 connexins form hemichannels in vitro.

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Section: Cx23a Forms Functional Hemichannelsmentioning

confidence: 79%

Cx23, a connexin with only four extracellular‐loop cysteines, forms functional gap junction channels and hemichannels

et al. 2007

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“…These membrane channels are inhibited by physiological concentrations of extracellular Ca 2ϩ (Trexler et al, 1996;Zampighi et al, 1999;Valiunas and Weingart, 2000;Bruzzone et al, 2001) Astrocytes show low [Ca 2ϩ ] o -activated currents consistent with currents through connexin hemichannels. These currents are not influenced by perfusion of the extracellular medium, suggesting that they are not mediated by an extracellular messenger released from cells (such as ATP).…”

Section: Modulation Of Low [Ca 2؉ ] O -Activated Currents By [Mg 2؉ ] Omentioning

confidence: 94%

Modulation of intercellular calcium signaling in astrocytes by extracellular calcium and magnesium

Stout

Charles

2003

Glia

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The extracellular concentrations of Ca 2ϩ and Mg 2ϩ are well known to play important roles in the function of the central nervous system. We examined the effects of extracellular Ca 2ϩ and Mg 2ϩ on ATP release and intercellular signaling in astrocytes. [Ca 2ϩ ] o -activated whole cell currents consistent with currents through connexin hemichannels. These currents were inhibited by extracellular Mg 2ϩ . We conclude that extracellular divalent cations modulate intercellular Ca 2ϩ signaling in astrocytes by modulating the release of ATP, possibly via connexin hemichannels.

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“…Thus, in an open channel, pore-lining residues should be uniquely accessible from either side of the membrane (Figure 1). Monitoring the open state of a channel requires single-channel recording, which, together with accessibility from either side, is readily achieved by using connexin hemichannels in excised inside-out or outside-out patch configurations (14). SCAM at the single channel level allows immediate separation of effects on gating from those on open channel properties and an ability to assess whether effects of modification are consistent with residence in the pore.…”

Section: Resultsmentioning

confidence: 99%

Pore-Lining Residues Identified by Single Channel SCAM Studies in Cx46 Hemichannels

Kronengold

Trexler²,

Bukauskas

et al. 2003

Cell Communication & Adhesion

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The substituted cysteine accessibility method was applied to single Cx46 hemichannels to identify residues that participate in lining the aqueous pore of channels formed of connexins. Criteria for assignment to the pore included reactivity to sulfydryl-specific methanethiosulfonate (MTS) reagents from both sides of an open hemichannel and observable effects on open channel properties. We demonstrate reactivity to MTS reagents over a stretch of seventeen amino acids, D51 through L35, that constitute segments of E1 and TM1. Qualitatively, the nature of the effects caused by the Cys substitutions alone and their modification with MTS reagents of either charge indicate side chain valence is most influential in determining single channel properties with D51 and L35 defining the extracellular and intracellular limits, respectively, of the identified porelining region. A number of Cys substitutions beyond L35 in TM1 caused severe alterations in hemichannel function and precluded assignment to the pore. Although all six subunits can be modified by smaller MTS reagents, modifications appear limited to fewer subunits with larger reagents.

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Voltage gating and permeation in a gap junction hemichannel.

Cited by 294 publications

References 18 publications

Cx23, a connexin with only four extracellular‐loop cysteines, forms functional gap junction channels and hemichannels

Cx23, a connexin with only four extracellular‐loop cysteines, forms functional gap junction channels and hemichannels

Modulation of intercellular calcium signaling in astrocytes by extracellular calcium and magnesium

Pore-Lining Residues Identified by Single Channel SCAM Studies in Cx46 Hemichannels

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