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| Item Type: | Article |
|---|---|
| Title: | Determinants of slow gating in ClC-0, the voltage-gated chloride channel of Torpedo marmorata |
| Creators Name: | Fong, P., Rehfeldt, A. and Jentsch, T.J. |
| Abstract: | Membrane hyperpolarization normally activates the slow gate of the Torpedo voltage-gated chloride channel (ClC-0). To elucidate the structural basis of this process, carboxy terminus truncation mutants and chimeras were constructed, expressed in Xenopus oocytes, and evaluated using a two-microelectrode voltage clamp. Introduction of stop codons at several positions between transmembrane domains 12 and 13 (D12 and D13) showed no expression, whereas a truncation just after D13 yielded wild-type currents. A chimera (022) entailing the substitution of the carboxy-terminal cytoplasmic tail after Lys-520 with the corresponding region of ClC-2 lacked slow gating, whereas a more conservative construct (chimera 002), in which D13 was replaced with its ClC-2 analog, retained its capacity to slow gate. These findings suggest that important structures reside within the interdomain stretch (IDS) between D12 and D13. Unlike ClC-2, in which transplantation of "ball" structures could restore gating to constitutively open mutants, transplantation of the ClC-0 IDS to the amino terminus of chimera 022 did not restore gating. Surprisingly, replacement of the IDS by the analogous regions of either ClC-1 or ClC-2 showed slow voltage-activated gating, although the gating was altered. Our findings lead us to conclude that both the functional expression and the slow voltage gating of ClC-0 rely on structures at the carboxy terminus of the channel. |
| Keywords: | Voltage Clamp, Chimera, Truncation, Animals, Xenopus Laevis |
| Source: | American Journal of Physiology |
| ISSN: | 0002-9513 |
| Publisher: | American Physiological Society |
| Volume: | 274 |
| Number: | 4 Pt 1 |
| Page Range: | C966-C973 |
| Date: | April 1998 |
| Official Publication: | http://ajpcell.physiology.org/cgi/content/abstract/274/4/C966 |
| PubMed: | View item in PubMed |
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