RGD Reference Report - Gap junction channels formed by coexpressed connexin40 and connexin43. - Rat Genome Database

Send us a Message



Submit Data |  Help |  Video Tutorials |  News |  Publications |  Download |  REST API |  Citing RGD |  Contact   

Gap junction channels formed by coexpressed connexin40 and connexin43.

Authors: Valiunas, V  Gemel, J  Brink, PR  Beyer, EC 
Citation: Valiunas V, etal., Am J Physiol Heart Circ Physiol. 2001 Oct;281(4):H1675-89.
RGD ID: 7207849
Pubmed: PMID:11557558   (View Abstract at PubMed)

Many cardiovascular cells coexpress multiple connexins (Cx), leading to the potential formation of mixed (heteromeric) gap junction hemichannels whose biophysical properties may differ from homomeric channels containing only one connexin type. We examined the potential interaction of connexin Cx43 and Cx40 in HeLa cells sequentially stably transfected with these two connexins. Immunoblots verified the production of comparable amounts of both connexins, cross-linking showed that both connexins formed oligomers, and immunofluorescence showed extensive colocalization. Moreover, Cx40 copurified with (His)(6)-tagged Cx43 by affinity chromatography of detergent-solubilized connexons, demonstrating the presence of both connexins in some hemichannels. The dual whole cell patch-clamp method was used to compare the gating properties of gap junctions in HeLa Cx43/Cx40 cells with homotypic (Cx40-Cx40 and Cx43-Cx43) and heterotypic (Cx40-Cx43) gap junctions. Many of the observed single channel conductances resembled those of homotypic or heterotypic channels. The steady-state junctional conductance (g(j,ss)) in coexpressing cell pairs showed a reduced sensitivity to the voltage between cells (V(j)) compared with homotypic gap junctions and/or an asymmetrical V(j) dependence reminiscent of heterotypic gap junctions. These gating properties could be fit using a combination of homotypic and heterotypic channel properties. Thus, whereas our biochemical evidence suggests that Cx40 and Cx43 form heteromeric connexons, we conclude that they are functionally insignificant with regard to voltage-dependent gating.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Gja1Ratregulation of cell communication by electrical coupling  IDA  RGD 
Gja5Ratregulation of cell communication by electrical coupling  IDA  RGD 

Molecular Function

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Gja1Ratconnexin binding  IPIGja5 (Rattus norvegicus) RGD 
Gja5Ratconnexin binding  IPIGja1 (Rattus norvegicus) RGD 

Objects Annotated

Genes (Rattus norvegicus)
Gja1  (gap junction protein, alpha 1)
Gja5  (gap junction protein, alpha 5)


Additional Information