Exchange of conductance and gating properties between gap junction hemichannels

@article{Hu1999ExchangeOC,
  title={Exchange of conductance and gating properties between gap junction hemichannels},
  author={X J Hu and Gerhard Dahl},
  journal={FEBS Letters},
  year={1999},
  volume={451}
}

Function of the voltage gate of gap junction channels: Selective exclusion of molecules

  • Yang QuG. Dahl
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 2002
TLDR
Xenopus oocytes expressing cx43 or cx46 are found to have an activated voltage gate that preferentially restricts the passage of larger ions, such as fluorescent tracer molecules and cAMP, while having little effect on the electrical coupling arising from the passing of small electrolytes.

Conductance of connexin hemichannels segregates with the first transmembrane segment.

TLDR
The first transmembrane segment (M1) was reciprocally exchanged between Cx46 and Cx32E(1)43 and exhibited conductances similar to that of the respective M1 donor, and contains important determinants of conductance of the connexin channel.

The Connexin Channel Pore: Pore-Lining Segments and Residues

TLDR
A number of studies have attempted to define the connexin pore in molecular terms and to reveal the key elements of the pore structure that may differ across connexins, but current views have not reached a consensus regarding the principal domains contributing to the pores.

Structural determinants underlying permeant discrimination of the Cx43 hemichannel

TLDR
A permeant-dependent, isoform-specific inhibition of connexin hemichannels is demonstrated, revealing that the outer segments of the pore-lining region, including the N terminus and the first extracellular loop, together with the C terminus preclude ion conductance of the open Cx43 hemichannel.

Single-channel SCAM Identifies Pore-lining Residues in the First Extracellular Loop and First Transmembrane Domains of Cx46 Hemichannels

TLDR
Gap junction channels provide an important pathway for direct intercellular transmission of signaling molecules and residues D51, G46, and E43 at the amino end of E1 are accessible to modification in open hemichannels to positively and negatively charged methanethiosulfonate reagents added to cytoplasmic or extracellular sides.

Structural determinants for the differences in voltage gating of chicken Cx56 and Cx45.6 gap-junctional hemichannels.

TLDR
Results show that two charged amino acids that are specific for the alpha3-group connexins (R9 in the N-terminus and E43 in the first extracellular loop) are important determinants for the difference in voltage-dependent gating between Cx45.6 and Cx56 hemichannels.

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TLDR
It is demonstrated by single channel recording that hemichannels comprised of rat Cx46 exhibit complex voltage gating consistent with there being two distinct gating mechanisms.

A chimeric connexin forming gap junction hemichannels

TLDR
A chimeric connexin consisting of cx32 where the first extracellular loop sequence is replaced by the corresponding cx43 sequence, cx32E143, forms conventional gap junction channels in the paired oocyte assay and induces a membrane conductance in single oocytes.

Three-dimensional structure of a recombinant gap junction membrane channel.

TLDR
Although not indicative for a particular type of secondary structure, the protein density that formed the extracellular vestibule provided a tight seal to exclude the exchange of substances with theextracellular milieu.

Structure of the MscL homolog from Mycobacterium tuberculosis: a gated mechanosensitive ion channel.

TLDR
The structure of the MscL homolog from Mycobacterium tuberculosis was determined by x-ray crystallography to 3.5 angstroms resolution and may serve as a model for other mechanosensitive channels, as well as the broader class of pentameric ligand-gated ion channels exemplified by the nicotinic acetylcholine receptor.

Connexin46, a novel lens gap junction protein, induces voltage-gated currents in nonjunctional plasma membrane of Xenopus oocytes

TLDR
Results suggest that unprocessed Cx46 induces nonselective channels in the oolemma that are voltage dependent and opened by large depolarizations, suggesting substantive lenticular posttranslational processing of the native translation product.

The structure of the potassium channel: molecular basis of K+ conduction and selectivity.

TLDR
The architecture of the pore establishes the physical principles underlying selective K+ conduction, which promotes ion conduction by exploiting electrostatic repulsive forces to overcome attractive forces between K+ ions and the selectivity filter.

Specific motifs in the external loops of connexin proteins can determine gap junction formation between chick heart myocytes.

TLDR
The ability of peptides containing the SRPTEK motif to interfere with the formation of gap junctions was enhanced by amino acids from the putative membrane‐spanning region and the steep portion of the dose‐response relation lay between 30 and 300 microM peptide.