The Voltage-gated Potassium Channel family Flashcards
(75 cards)
Name the 3 physiological functions that the potassium channels contribute to?
- Control of cell volume. 2. Control of membrane potential and cell excitability. 3. Secretion of salts, hormones & neurotransmitters.
Name the 5 regulators of the potassium channels activity?
- Numerous hormones & transmitters. 2. Voltage across membrane. 3. Conc. of calcium or ATP in cytoplasm. 4. Kinases and phophatases. 5. G-proteins
Name the 3 structures of the potassium channels?
- 6 transmembrane one-pore 2. Two transmembrane one-pore 3. Four transmembrane two-pore
Properties of the 6-transmembrane segment potassium channels?
- alpha subunit similar in shape to the sodium and calcium channels. 2. Contains S4 voltage sensor and P region.
Name the four channels that are part of the 6-transmembrane segment family?
- hERG channels. 2. Voltage-activated potassium channels. 3. Calcium activated potassium channels. 4. KCNQ channels
What is the role of the voltage-activated potassium channels?
Responsible for shaping of the action potential.
Name the main two types of voltage-activated potassium channels?
- Inactivating ‘A’ type. 2. Non-inactivating
Properties of the inactivating ‘A’ type of voltage-activated potassium channels?
Display rapid inactivation following opening. Ball and chain form of inactivation

Properties of the non-inactivating type of voltage-activated potassium channels?
Slow inactivation.

Describe the “ball and chain” form of inactivation?
First 20 amino acids forms compact hydrophobic charged surface domains which plugs the channel from the inside. Prevents potassium efflux
Describe the properties of the N-type inactivation?
Ball and chain inactivation mechanism.
Where is the ball made from the ball and chain inactivation?
Set of amino acids in the S4-S5 loop.
What controls the activity of the potassium channel?
Controlled by the conc. of cytoplasmic calcium. Important in limiting calcium entry and neuronal excitability.
Name the 3 subtypes of calcium-activated potassium channels?
- Large conductance (maxi-K) 2. Intermediate (IK) conductance. 3. Small (SK) conductance.
What channel is important for the slow afterhyperpolarisation observed after AP discharge?
Small conductance channels are responsible for this.
Where are maxi-K channels expressed?
Ubiquitously (found everywhere) Help shape APs in neurones and regulate transmitter release. In smooth muscle: regulate contractile activity and tone.
What controls the opening of maxi-K channels?
Transmembrane voltage as they are voltage-dependent.
What is the activation of maxi-K channels dependent on?
The intracellular calcium conc. The more calcium conc. in the cell: the less electrical energy is needed to open it.
Describe the beta and alpha subunits of the maxi-K channel?
beta: 2 transmembrane domians. Alpha: 6.

What part of the alpha subunit is important for the function of the maxi-k channel?
The long COOH terminus
What gene encodes for the Maxi-K alpha subunit?
Slo gene.
What part is unique to maxi-K channels?
SO region
Name the 4 types of beta subunits?
b1-4
Role of the beta subunits in the maxi-K channel?
Alter sensitivity to calcium and voltage, activation kinetics.


