Functional Characterization of Canine Connexin45 |
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Authors: | E Steiner L Ebihara |
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Institution: | (1) Department of Pharmacology, Columbia University, New York, NY 10032, US |
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Abstract: | Three gap junctional proteins have been identified in canine ventricular myocytes: connexin 43 (Cx43), connexin 45 (Cx45),
and connexin 40 (Cx40). We have characterized the functional properties of canine Cx45 and examined how Cx45 functionally
interacts with Cx43 in Xenopus oocyte pairs. Homotypic pairs expressing Cx45 were well coupled. Heterotypic pairs composed of Cx45 paired with either Cx43
or Cx38 also developed high levels of conductance. Junctional currents in the heterotypic pairs displayed a highly asymmetrical
voltage dependence. The kinetics and steady-state voltage dependence of the heterotypic channels more closely resembled those
of the Cx45 channels when the Cx45 cRNA-injected cell was relatively negative suggesting that the Cx45 connexon closes for
relative negativity at the cytoplasmic end of the channel. We also show that homotypic and heterotypic channels composed of
Cx45 and Cx43 exhibit differences in pH
i
sensitivity.
Received: 18 August 1995/Revised: 21 November 1995 |
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Keywords: | : Intercellular communication — Connexin — Heart — Gap junction |
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