PUBLICATION
Biophysical Characterization of Zebrafish Connexin35 Hemichannels
- Authors
- Valiunas, V., Mui, R., McLachlan, E., Valdimarsson, G., Brink, P.R., and White, T.W.
- ID
- ZDB-PUB-040804-5
- Date
- 2004
- Source
- American journal of physiology. Cell physiology 287(6): C1596-C1604 (Journal)
- Registered Authors
- Valdimarsson, Gunnar
- Keywords
- connexin, hemichannel, gating, retina
- MeSH Terms
-
- Animals
- Connexins/chemistry
- Connexins/genetics*
- Connexins/metabolism*
- Eye Proteins/chemistry
- Eye Proteins/genetics*
- Eye Proteins/metabolism*
- Gap Junctions/physiology
- Ion Channel Gating/physiology*
- Kinetics
- Membrane Potentials/physiology
- Oligonucleotides, Antisense
- Oocytes/physiology
- Patch-Clamp Techniques
- Protein Structure, Quaternary
- RNA, Complementary
- Transfection
- Xenopus
- Zebrafish
- PubMed
- 15282192 Full text @ Am. J. Physiol. Cell Physiol.
Citation
Valiunas, V., Mui, R., McLachlan, E., Valdimarsson, G., Brink, P.R., and White, T.W. (2004) Biophysical Characterization of Zebrafish Connexin35 Hemichannels. American journal of physiology. Cell physiology. 287(6):C1596-C1604.
Abstract
A subset of connexins can form unopposed hemichannels in expression systems providing an opportunity to compare hemichannel gating properties with those of intact gap junction channels. Zebrafish Cx35 is a member of the Cx35/Cx36 subgroup of connexins highly expressed in the retina and brain. Here we show that Cx35 expression in Xenopus oocytes and N2A cells produced large outward whole cell currents on cell depolarization. Using whole-cell, cell-attached and excised patch configurations we obtained multichannel and single channel current recordings attributable to the Cx35 hemichannels (Ihc) that were activated and increased by stepwise depolarization of Vm and deactivated by hyperpolarization. The currents were not detected in untransfected N2A cells, or control oocytes injected with antisense Cx38. However, water injected oocytes that were not antisense treated showed activities attributable to Cx38 hemichannels that were easily distinguishable from Cx35 hemichannels by a significantly larger unitary conductance (250-320 pS). The unitary conductance (gammahc) of Cx35 hemichannels exhibited a pronounced Vm-dependence i.e. gammahc increased/decreased with relative hyperpolarization/depolarization (gammahc was 72 pS at Vm=-100 mV and 35 pS at Vm=100 mV). Extrapolation to Vm=0 mV predicted a gammahc of 48 pS, suggesting a unitary conductance of intact Cx35 gap junction channels of ~24 pS. Channel gating was also Vm-dependent, open time declined with negative Vm, and increased with positive Vm. The ability to break down the complex gating of intact intercellular channels into component hemichannels in vitro will help to evaluate putative physiological roles for hemichannels in vivo.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping