期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 275, 期 18, 页码 13343-13348出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.275.18.13343
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资金
- Telethon [1079] Funding Source: Medline
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 approximate to 18 pS for KCNQ2 and approximate to 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.
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