Question

Which statement is INCORRECT regarding voltage-gated potassium channels?

- The gating of the channel involves movements of transmembrane helices.
- The K+ is transported down its concentration gradient.

- A cytoplasmic inactivation peptide blocks the channel in response to voltage changes.

- K+ coordinates to C=0 groups in the channel.

- All of the above.

Answer 1

Ans is C.

Voltage gated potassium channel is a transmembrane channel which helps in transfer of Potassium ion across the cell membrane from within the cell to the exterior along its electrochemical gradient.
'the potassium channel consists of four subunits formed by alpha and beta subunit. They form a tetramer which form a enclosed channel to pass the potassium ion. Each subunit is concocting of 6 alpha helix.

The voltage which opens the channel provides an electric field which causes movement of the alpha helixes of the transmembrane segment in the lipid bilayer, causes opening of the channel.

when potassium ion passes through the pore, the carbonyl group of channel protein form an interaction and strip off the water molecule attached with the potassium ion. This helps in transfer of the ion.

Though there is a block protein which blocks the channel during inactivation, but  it is formed by the amino terminal of the K+ channel domain, not by a cytoplasmic protein.