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Functional properties of mouse connexin30.2 expressed in the conduction system of the heart
- Source :
- Circulation research. 96(11)
- Publication Year :
- 2005
-
Abstract
- Gap junction channels composed of connexin (Cx) 40, Cx43, and Cx45 proteins are known to be necessary for impulse propagation through the heart. Here, we report mouse connexin30.2 (mCx30.2) to be a new cardiac connexin that is expressed mainly in the conduction system of the heart. Antibodies raised to the cytoplasmic loop or the C-terminal regions of mCx30.2 recognized this protein in mouse heart as well as in HeLa cells transfected with wild-type mCx30.2 or mCx30.2 fused with enhanced green fluorescent protein (mCx30.2-EGFP). Immunofluorescence analyses of adult hearts yielded positive signals within the sinoatrial node, atrioventricular node, and A-V bundle of the cardiac conduction system. Dye transfer studies demonstrated that mCx30.2 and mCx30.2-EGFP channels discriminate poorly on the basis of charge, but do not allow permeation of tracers >400 Da. Both mCx30.2 and mCx30.2-EGFP gap junctional channels exhibited weak sensitivity to transjunctional voltage (V j ) and a single channel conductance of ≈9 pS, which is the lowest among all members of the connexin family measured in HeLa cell transfectants. HeLa mCx30.2-EGFP transfectants when paired with cells expressing Cx40, Cx43, or Cx45 formed functional heterotypic gap junction channels that exhibited low unitary conductances (15 to 18 pS), rectifying open channel I-V relations and asymmetric V j dependence. The electrical properties of homo- and hetero-typic junctions involving mCx30.2 may contribute to slow propagation velocity in nodal tissues and directional asymmetry of excitation spread in the AV nodal region.
- Subjects :
- Physiology
Connexin
Fluorescent Antibody Technique
Biology
Cell junction
Connexins
Permeability
Article
Mice
Heart Conduction System
medicine
Connexin 30
Animals
Humans
RNA, Messenger
Sinoatrial node
Gap junction
Gap Junctions
Anatomy
Atrioventricular node
medicine.anatomical_structure
Cytoplasm
Biophysics
Electrical conduction system of the heart
Cardiology and Cardiovascular Medicine
NODAL
HeLa Cells
Subjects
Details
- ISSN :
- 15244571
- Volume :
- 96
- Issue :
- 11
- Database :
- OpenAIRE
- Journal :
- Circulation research
- Accession number :
- edsair.doi.dedup.....3b34fe0632e8b1908219df4ff921c7e4