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| Item Type: | Article |
|---|---|
| Title: | Surface expression and single channel properties of KCNQ2/KCNQ3, M-type K+ channels involved in epilepsy |
| Creators Name: | Schwake, M., Pusch, M., Kharkovets, T. and Jentsch, T.J. |
| Abstract: | Mutations in either KCNQ2 or KCNQ3 underlie benign familial neonatal convulsions (BFNC), an inherited epilepsy. The corresponding proteins are co-expressed in broad regions of the brain and associate to heteromeric K(+) channels. These channels mediate M-type currents that regulate neuronal excitability. We investigated the basis for the increase in currents seen after co-expressing these subunits in Xenopus oocytes. Noise analysis and single channel recordings revealed a conductance of approximately 18 pS for KCNQ2 and approximately 7 pS for KCNQ3. Different conductance levels (ranging from 8 to 22 pS) were seen upon co-expression. Their weighted average is close to that obtained by noise analysis (16 pS). The open probability of heteromeric channels was not increased significantly. Co-expression of both subunits increased the surface expression of KCNQ2 and KCNQ3 by factors of 5 and >10, respectively. A KCNQ2 mutant associated with BFNC that has a truncated cytoplasmic carboxyl terminus did not reach the surface and failed to stimulate KCNQ3 surface expression. By contrast, several BFNC-associated missense mutations in KCNQ2 or KCNQ3 did not alter their surface expression. Thus, the increase in currents seen upon co-expressing KCNQ2 and KCNQ3 is predominantly due to an increase in surface expression, which is dependent on an intact carboxyl terminus. |
| Keywords: | Epilepsy, Gene Expression Regulation, Ion Channel Gating, KCNQ2 Potassium Channel, KCNQ3 Potassium Channel, Mutation, Patch-Clamp Techniques, Voltage-Gated Potassium Channels, Animals |
| Source: | Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Volume: | 275 |
| Number: | 18 |
| Page Range: | 13343-13348 |
| Date: | 5 May 2000 |
| Official Publication: | https://doi.org/10.1074/jbc.275.18.13343 |
| PubMed: | View item in PubMed |
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