Final answer:
Delayed K+ rectifier channels are voltage-gated K+ channels critical for repolarization of the cell membrane post-action potential. They differ from other K+ channels by opening more slowly and closing with a delay. These channels adopt three states: closed, open, and inactivated; they are influenced by membrane potential and the duration of voltage threshold maintenance.
Step-by-step explanation:
Delayed K+ Rectifier Channels
Delayed K+ rectifier channels are a type of voltage-gated K+ channel that plays a crucial role in the repolarization of the cell membrane after an action potential. They are different from other K+ channels in that they open more slowly and close with a delay when the membrane potential repolarizes. These channels have three conformational states: closed (before the action potential), open (allowing K+ to leave the cell during repolarization), and inactivated (shortly after the action potential). Two main factors influence the type of conformational change that occurs in these channels: the membrane potential and the duration for which the voltage threshold is maintained.
Factors Influencing Conformational Changes
- Membrane potential - The delayed K+ channels are sensitive to particular voltage thresholds, specifically around -50 mV.
- Duration of voltage threshold - Once the membrane potential reaches the voltage threshold, the time it is maintained will affect whether the channel opens or transitions to the inactivated state.
These delayed K+ rectifier channels are essential for the proper functioning of cells, particularly in cardiac and neural tissues, where they help restore the resting membrane potential and contribute to the rhythmicity of heartbeats and the transmission of neural signals.