Coupling asymmetry of heterotypic connexin 45/connexin 43-EGFP gap junctions: Properties of fast and slow gating mechanisms

Feliksas F. Bukauskas, A. Bukauskiene Angele, Vytautas Verselis, Michael V. L. Bennett

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Abstract

Although fast and slow gating mechanisms have been described in gap junctions (GJs), their relative contributions to dependence on transjunctional voltage, Vj, is still unclear. We used cell lines expressing wild-type connexin 45 (Cx45) and connexin 43 fused with enhanced green fluorescent protein (Cx43-EGFP) to examine mechanisms of gating in homo- and heterotypic GJs formed of these connexins. Macroscopically Cx45/Cx45 channels show high sensitivity to Vi. Cx45 channels demonstrate two types of gating: fast transitions between open and residual states and slow transitions between open and completely closed states. Single-channel conductance of the Cx45 channel is ≈32 pS for the open state and ≈4 pS for the residual state. Cx45/Cx43-EGFP heterotypic junctions exhibit very asymmetrical Vj gating with the maximum junctional conductance shifted to Vj positive on the Cx45 side. Conductance of single Cx45/Cx43-EGFP channels is ≈55 pS for the open state and ≈4 pS for the residual state, values consistent with the simple-series connection of Cx45 and Cx43-EGFP hemichannels. At Vi = 0, the slow gate of many Cx45 hemichannels is closed in both homotypic Cx45/Cx45 and heterotypic Cx45/Cx43-EGFP junctions. Fast and slow Vj gates of both Cx45 and Cx43 hemichannels close for relative negativity at their cytoplasmic end. Coupling mediated by Cx45/Cx43-EGFP junctions can exhibit asymmetry that can be strongly modulated by small changes in difference of holding potentials. Cx45/Cx43 junctions are likely to be found in brain and heart and may mediate rectifying electrical transmission or modulatable chemical communication.

Original languageEnglish (US)
Pages (from-to)7113-7118
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number10
DOIs
StatePublished - May 14 2002

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Connexin 43
Gap Junctions
connexin 45
Connexins

Keywords

  • Channels
  • Electrical coupling
  • Intercellular communication
  • Rectifaction
  • Voltage gating

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

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title = "Coupling asymmetry of heterotypic connexin 45/connexin 43-EGFP gap junctions: Properties of fast and slow gating mechanisms",
abstract = "Although fast and slow gating mechanisms have been described in gap junctions (GJs), their relative contributions to dependence on transjunctional voltage, Vj, is still unclear. We used cell lines expressing wild-type connexin 45 (Cx45) and connexin 43 fused with enhanced green fluorescent protein (Cx43-EGFP) to examine mechanisms of gating in homo- and heterotypic GJs formed of these connexins. Macroscopically Cx45/Cx45 channels show high sensitivity to Vi. Cx45 channels demonstrate two types of gating: fast transitions between open and residual states and slow transitions between open and completely closed states. Single-channel conductance of the Cx45 channel is ≈32 pS for the open state and ≈4 pS for the residual state. Cx45/Cx43-EGFP heterotypic junctions exhibit very asymmetrical Vj gating with the maximum junctional conductance shifted to Vj positive on the Cx45 side. Conductance of single Cx45/Cx43-EGFP channels is ≈55 pS for the open state and ≈4 pS for the residual state, values consistent with the simple-series connection of Cx45 and Cx43-EGFP hemichannels. At Vi = 0, the slow gate of many Cx45 hemichannels is closed in both homotypic Cx45/Cx45 and heterotypic Cx45/Cx43-EGFP junctions. Fast and slow Vj gates of both Cx45 and Cx43 hemichannels close for relative negativity at their cytoplasmic end. Coupling mediated by Cx45/Cx43-EGFP junctions can exhibit asymmetry that can be strongly modulated by small changes in difference of holding potentials. Cx45/Cx43 junctions are likely to be found in brain and heart and may mediate rectifying electrical transmission or modulatable chemical communication.",
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T1 - Coupling asymmetry of heterotypic connexin 45/connexin 43-EGFP gap junctions

T2 - Properties of fast and slow gating mechanisms

AU - Bukauskas, Feliksas F.

AU - Angele, A. Bukauskiene

AU - Verselis, Vytautas

AU - Bennett, Michael V. L.

PY - 2002/5/14

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N2 - Although fast and slow gating mechanisms have been described in gap junctions (GJs), their relative contributions to dependence on transjunctional voltage, Vj, is still unclear. We used cell lines expressing wild-type connexin 45 (Cx45) and connexin 43 fused with enhanced green fluorescent protein (Cx43-EGFP) to examine mechanisms of gating in homo- and heterotypic GJs formed of these connexins. Macroscopically Cx45/Cx45 channels show high sensitivity to Vi. Cx45 channels demonstrate two types of gating: fast transitions between open and residual states and slow transitions between open and completely closed states. Single-channel conductance of the Cx45 channel is ≈32 pS for the open state and ≈4 pS for the residual state. Cx45/Cx43-EGFP heterotypic junctions exhibit very asymmetrical Vj gating with the maximum junctional conductance shifted to Vj positive on the Cx45 side. Conductance of single Cx45/Cx43-EGFP channels is ≈55 pS for the open state and ≈4 pS for the residual state, values consistent with the simple-series connection of Cx45 and Cx43-EGFP hemichannels. At Vi = 0, the slow gate of many Cx45 hemichannels is closed in both homotypic Cx45/Cx45 and heterotypic Cx45/Cx43-EGFP junctions. Fast and slow Vj gates of both Cx45 and Cx43 hemichannels close for relative negativity at their cytoplasmic end. Coupling mediated by Cx45/Cx43-EGFP junctions can exhibit asymmetry that can be strongly modulated by small changes in difference of holding potentials. Cx45/Cx43 junctions are likely to be found in brain and heart and may mediate rectifying electrical transmission or modulatable chemical communication.

AB - Although fast and slow gating mechanisms have been described in gap junctions (GJs), their relative contributions to dependence on transjunctional voltage, Vj, is still unclear. We used cell lines expressing wild-type connexin 45 (Cx45) and connexin 43 fused with enhanced green fluorescent protein (Cx43-EGFP) to examine mechanisms of gating in homo- and heterotypic GJs formed of these connexins. Macroscopically Cx45/Cx45 channels show high sensitivity to Vi. Cx45 channels demonstrate two types of gating: fast transitions between open and residual states and slow transitions between open and completely closed states. Single-channel conductance of the Cx45 channel is ≈32 pS for the open state and ≈4 pS for the residual state. Cx45/Cx43-EGFP heterotypic junctions exhibit very asymmetrical Vj gating with the maximum junctional conductance shifted to Vj positive on the Cx45 side. Conductance of single Cx45/Cx43-EGFP channels is ≈55 pS for the open state and ≈4 pS for the residual state, values consistent with the simple-series connection of Cx45 and Cx43-EGFP hemichannels. At Vi = 0, the slow gate of many Cx45 hemichannels is closed in both homotypic Cx45/Cx45 and heterotypic Cx45/Cx43-EGFP junctions. Fast and slow Vj gates of both Cx45 and Cx43 hemichannels close for relative negativity at their cytoplasmic end. Coupling mediated by Cx45/Cx43-EGFP junctions can exhibit asymmetry that can be strongly modulated by small changes in difference of holding potentials. Cx45/Cx43 junctions are likely to be found in brain and heart and may mediate rectifying electrical transmission or modulatable chemical communication.

KW - Channels

KW - Electrical coupling

KW - Intercellular communication

KW - Rectifaction

KW - Voltage gating

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U2 - 10.1073/pnas.032062099

DO - 10.1073/pnas.032062099

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AN - SCOPUS:0037076384

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JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

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