Ion channels, such as the K+ channel, can have open and closed forms that respon

Question

Ion channels, such as the K+ channel, can have open and closed forms that respond to membrane potential. In addition, an amino-terminal domain, called the inacivation domain or inactivation gate, can block the channel. This is called the ball and chain model of channel inactivation.

Identify the statements that corrently describe the ball and chain model.

There is more than one true statement. Select all the apply.

1. After depolarization and channel opening, the inactivation gate soon occules the open channel.

2. A mutation causing the loss of the inactivation gate in the K+ channels could result in a membrane that undergoes repolarization more slowly.

3. A shorter "tether" or "chain" peptide strand attached to the inactivation domain would increase the time required to inactivate the K+ channel.

4. The inactivation gate can only inactivate a channel that has closed in response to depolarization.

Explanation / Answer

The process of depolarization results in opening of channels by transition of the activation gate and then enters a long-living non-conducting and inactivated state. The inactivation gate occludes the ion pore until the membrane is depolarized.

In ball and chain method, the inactivation is achieved by tethering of inactivation particle (ball) to the cytoplasmic face by a protease cleavable domain.

A mutation leads to loss of the inactivation gate in the K+ channels, which results in a membrane that undergoes repolarization more slowly.

Thus, the correct options among the following are 1 and 2.

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