Cytoplasmic residues influence the voltage-dependence of the gating of human K+ channels.
Shaker type potassium channels are strongly voltage dependent and potassium selective. Kv1.4 channels from a variety of sources exhibit a much shallower voltage-dependence of activation than other members of the family. We have made a chimeric construct consisting of the N-terminal chain of hKv1.1 spliced onto the transmembrane portion of hKv1.4 (IN/4). When expressed in Xenopus oocytes, the chimeric channel exhibits a voltage dependence that is similar to hKv1.1 although the voltage sensing and transduction machinery presumably reside in the transmembrane portion of the channel. Loss of the N-terminal ball and chain from hKv1.4 is not responsible for this as a truncation construct, starting close to the splice junction, has the same voltage-dependence as full length hKv1.4. We suggest that residues from the N-terminal chain of hKv1.1 interact with the machinery that transduces movement of the voltage sensor into channel opening. If so, this chimeric construct could provide a handle to the identification of elements of this transduction machinery.
Varshney
A
A
Laboratory of Membrane Biophysics, National Centre for Biological Sciences, Bangalore, India.
Mathew
M K
MK
D000818:Animals; D002462:Cell Membrane / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry*; D006801:Humans; D051662:Kv1.1 Potassium Channel; D051665:Kv1.4 Potassium Channel; D009865:Oocytes / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D019154:Protein Splicing / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics*; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism
C496946:KCNA1 protein, human; C496977:KCNA4 protein, human; D051665:Kv1.4 Potassium Channel; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; D051662:Kv1.1 Potassium Channel