Determinants of potassium channel assembly localised within the cytoplasmic C-terminal domain of Kv2.1.
The C-terminal domain of the voltage-gated potassium channel Kv2.1 is shown to have a role in channel assembly using dominant negative experiments in Xenopus oocytes. Kv2.1 channel polypeptides were co-expressed with a number of polypeptide fragments of the cytosolic C-terminus and the assembly of functional channel homotetramers quantified electrophysiologically using the two electrode voltage clamp technique. Co-expression of C-terminal polypeptides corresponding to the final 440, 318, 220 and 150 amino acid residues of Kv2.1 all resulted in a significant reduction in the functional expression of the full-length channel. A truncated version of Kv2.1 lacking the final 318 amino acids of the C-terminal domain (Kv2. 11-535) exhibited similar electrophysiological properties to the full-length channel. Co-expression with either the 440 or 318 residue polypeptides resulted in a reduction in the activity of the truncated channel. In contrast, the 220 and 150 residue C-terminal fragments had no effect on Kv2.11-535 activity. These data demonstrate that C-terminal interactions are important for driving Kv2.1 channel assembly and that distinct regions of the C-terminal domain may have differential effects on the formation of functional tetramers.
Bentley
G N
GN
School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. bmbgnb@leeds.ac.uk
Brooks
M A
MA
O'Neill
C A
CA
Findlay
J B
JB
D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D015870:Gene Expression; D009154:Mutation; D009865:Oocytes / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary / Q000235:genetics; D051669:Shab Potassium Channels; D014982:Xenopus laevis
D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D051669:Shab Potassium Channels