Functional expression and biophysical properties of polymorphic variants of the human gap junction protein connexin37.
Biochem Biophys Res Commun
; 274(1): 216-24, 2000 Jul 21.
Article
en En
| MEDLINE
| ID: mdl-10903921
Connexin37 (Cx37) forms gap junction channels between endothelial cells, and two polymorphic Cx37 variants (Cx37-S319 and Cx37-P319) have been identified with a possible link to atherosclerosis. We studied the gap junction channel properties of these hCx37 polymorphs by expression in stably transfected communication-deficient cells (N2A and RIN). We also expressed a third, truncated variant (Cx37-fs254Delta293) and Cx37 constructs containing epitope tags added to their amino or carboxyl termini. All Cx37 constructs were produced by the transfected cells as demonstrated by RT-PCR and immunoblotting and trafficked to appositional surfaces between cells as demonstrated by immunofluorescence microscopy. Dual whole cell patch-clamping studies demonstrated that Cx37-P319, Cx37-S319, and Cx37-fs254Delta293 had large unitary conductances ( approximately 300 pS). However, addition of an amino terminal T7 tag (T7-Cx37-fs254Delta293) produced a single channel conductance of 120-145 pS with a 24-30 pS residual state. Moreover, the kinetics of the voltage-dependent decline in junctional current for T7-Cx37-fs254Delta293 were significantly slower than for the wild type, implying a destabilization of the transition state. These data suggest that the amino terminus of Cx37 plays a significant role in gating as well as conductance. The carboxyl terminal tail has lesser influence on unitary conductance and inactivation kinetics.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Uniones Comunicantes
/
Conexinas
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Biochem Biophys Res Commun
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos