Kir2.1

I will praise Thee; for I am fearfully and wonderfully made.

Psalm 139:14

"The central nervous system of man and animals
depends on electricity: the ability to maintain a voltage between the inside and outside of a cell membrane.

Q: How can an electrical voltage be achieved by a cell?
A: Osmosis, a law of nature, tends to move substances at high concentration toward areas of low concentration until equilibrium is reached. 

Active transport, by contrast, is a key part of life. 

It requires pushing materials against the concentration gradient (see video).
---The cell achieves active transport by use of molecular machines: membrane channels that can selectively filter needed materials (atoms, molecules or ions) and move them against the gradient where they would otherwise “want” to go. 

These include aquaporins that filter water, vesicles that can package and move molecular cargoes, and the amazing “voltage-gated” channels that can move ions. One of those, Kir2.1, has been elucidated in exquisite detail by scientists at the Sorbonne University in Paris.

Kir2.1 is a “rectifier” – a term that will be familiar to electronics
enthusiasts. Rectifiers allow current to flow one way. In electronics, rectifiers can turn alternating current (AC) to direct current (DC). Cell rectifiers do essentially the same thing: they rectify charges from one side of a divide to the other, making them go one way.

For the cell membrane to rectify charges (i.e., create a voltage), positively-charged ions like potassium (K+) must be pumped through the channel to the inner membrane. 

A series of four “gates” ensure the one-way passage of these tiny ions. 

First is a “selectivity filter” that collects the ions. These pass rapidly down constrictions that open and close just enough to let the

potassium ions through while blocking other molecules and ions.
The channel is thus self-regulating, sensing the voltage and opening or blocking its constrictions according to need. If that weren’t amazing enough for an electronics device at the nano scale, this channel also receives signals that make it respond to changing environments. The authors list four examples.
They also say that Kir channels are coded by 16 genes,--

----which implies that the protein parts must be delivered from the nucleus to ribosomes and then delivered to sites on the membrane where they will be needed. 

----The channels must be inserted into the membrane in the right orientation, implying additional quality control mechanisms.

For an interesting look at the element potassium (K), where it is found on earth, and how it gets incorporated into living things, see this video about potash on the popular YouTube channel Veritasium.
*Most of us live moment by moment unaware of all the designed machines inside of us that keep us ticking.
We should learn more about some of them just to increase our awe of life and stand humbly before the Creator who designed these wonders." 

CEH