Potassium Channel
This Jmol Exploration was created using the Jmol Exploration Webpage Creator from the MSOE Center for BioMolecular Modeling.
In the cell membrane, there are diversity membrane proteins for any function of cell. The membrane protein controls the access of kind of materials such as ions, small protein molecules. One of the membrane protein is the Potassium channel. The potassium channel adjusts the enter of potassium ions(K+). Because there is a pore for the potassium ions in this channel, the potassium ions can go to outside of cell.
As shown in the jmol model, the potassium channel is made up of four subunits. Each subunit has identical shape. X-ray analysis found that four subunits form the cone shaped filter. Also the filter of pore in potassium channel is located on its outer end. When potassium ion should enter the inside of cell, the potassium ion is lacated on the center of potassium ion. In this type of potassium channel called the ligand-gated channel. The ligand-gated channel shows signaling by the signal molecule that is ligand. If the signal molecule approaches to the potassium channel, the potassium channel would be opend to get the potassium ion.
Potassium ChannelThe potassium channel is made up of four identical subunits. In this jmol model, there is only one subnit of them. One subunit has the two long α-helix structure, and they are connected through the other α-helix structure. Almost part of this subunit has hydrophobic side.
one of four subunits in the potassium channel The most important function of potassium channel is that it can pass away through their selecting. When signaling molecules as the ligand meet the potassium channel, it bounds to the potassium channel. The ligand is hydrated on the outside of cell. However, as hydrated ligand pass away the potassium channel, the potassium channel can remove the shell of hydration from ligand.
In the subunit of potassium channel, there are carbonyl oxygens that have strong electro-negativity and cation-attractive. Thus, the potassium ions can bind with this area. However, becasue of the size of pore in potassium channel, the other ion likes sodium ion cannot enter to outside through this channel.
The calcium activated potassium channel is one of the potassium channel. There are some of calcium activated potassium channel such as BK channel, IK channel, and SK channel. The most common calcium activated potassium channel is the BK channel. The BK channel is motivated by the voltage-gated and calcium modulated channel.
The calcium activated potassium channel has a very important role in the nervous system in the human body. When the cell membrane get some of stimulus, the potential goes to positive. And the calcium channel is opened. By this step, the potassium channel is also opened. However, there is a difference of their speed. Therefore, the concentration of each ion is controlled. Likewise this case, the potassium channel is commonly cooperated with the other channel in cell membrane.
1. https://voer.edu.vn
2. Faber.ES, Sah.P, Calcium-activated potassium channels: multiple contributions to neuronal function, 2003, Neuroscientist;181-94
3.Vergara.C, Latorre.R, Marrion.NV, Adelman.JP. Calcium-activated potassium channels, 1998, Curr Opin Neurobiol;321-9.
4. Armstrong.C, The vision of the pore, Science; 280:56?7.
5.Thomas.M, Jayatilaka.D, Corry.B, The predominant role of coordination number in potassium channel selectivity, Biophysical Journal;93:2635?43