کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1944284 | 1053203 | 2013 | 11 صفحه PDF | دانلود رایگان |

• The mouse ClC-K1 Cl− channel has properties similar to those of ClC-Ka or rat ClC-K1.
• ClC-K1 has a single-channel conductance of ~ 40 pS and is activated on depolarization.
• Insertion of the V166E mutation in ClC-K1 revealed the activity of the protopore.
• Barttin increases ClC-K1 surface expression but currents are detected in its absence.
• The unit conductance and voltage dependence of ClC-K1 are not affected by Barttin.
Several Cl− channels have been described in the native renal tubule, but their correspondence with ClC-K1 and ClC-K2 channels (orthologs of human ClC-Ka and ClC-Kb), which play a major role in transcellular Cl− absorption in the kidney, has yet to be established. This is partly because investigation of heterologous expression has involved rat or human ClC-K models, whereas characterization of the native renal tubule has been done in mice. Here, we investigate the electrophysiological properties of mouse ClC-K1 channels heterologously expressed in Xenopus laevis oocytes and in HEK293 cells with or without their accessory Barttin subunit. Current amplitudes and plasma membrane insertion of mouse ClC-K1 were enhanced by Barttin. External basic pH or elevated calcium stimulated currents followed the anion permeability sequence Cl− > Br− > NO3− > I−. Single-channel recordings revealed a unit conductance of ~ 40 pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~ − 65 mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~ 20 pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~ + 25 mV. The unit conductance and voltage dependence of wild-type and V166E ClC-K1 were not affected by Barttin. Owing to their strikingly similar properties, we propose that the ClC-K1/Barttin complex is the molecular substrate of a chloride channel previously detected in the mouse thick ascending limb (Paulais et al., J Membr. Biol, 1990, 113:253–260).
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Journal: Biochimica et Biophysica Acta (BBA) - Biomembranes - Volume 1828, Issue 11, November 2013, Pages 2399–2409