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Understanding SK1, a channel protein that doesn’t act like a channel protein

11.07.2019

In a nutshell: Researchers have discovered the role of a protein in rat brain cells that does not behave as expected.

View Paper Abstract

Understanding SK1, a channel protein that doesn’t act like a channel protein

Cells in the brain communicate with each other by sending and receiving electrical signals. This activity transmits information from one brain region to another, which enables the brain to carry out its various functions.

Brain cells make different types of proteins that affect their electrical behaviour. One group of proteins, called small-conductance calcium-activated potassium channels (SK channels), helps to control the movement of electrically charged molecules across the cell membrane. When the concentration of calcium inside a brain cell reaches a certain level, SK channels are activated, allowing potassium to cross from the inside of the cell to the outside. This reduces the cell’s electrical activity, decreasing the number of signals that it transmits.

In mammals, three types of SK channel – SK1, SK2 and SK3 – are found throughout the brain. Studies in rats have shown that SK2 and SK3 are embedded in the cell membrane and act as channel proteins. However, SK1 does not end up in the cell membrane and does not seem to affect the electrical behaviour of brain cells.

To understand the role of SK1, Brain Function CoE researchers at the University of Queensland, led by chief investigator Pankaj Sah, looked more closely at brain cells in rats. In particular, they investigated how SK1 affected the activity of other SK channels.

The team found that after SK1 is made, it stays in a compartment inside the cell, rather than moving to the cell membrane. When SK2 is in the same compartment, the two proteins bind together, which prevents SK2 from moving to the cell membrane as well.

Rather than acting as a channel itself, SK1 seems to control the amount of SK2 in the cell membrane. In this way, SK1 can indirectly change the electrical activity of rat brain cells and, possibly, the transmission of information across the brain.

Next steps:
The researchers are investigating whether SK1 can affect the activity of SK2 in inflammation and disease. They are also interested in testing if any mutations within SK1 are linked to specific diseases in humans.


Reference:
Autuori, E., Sedlak, P., Xu, L., Ridder, M. C., Tedoldi, A., & Sah, P. (2019). RSK1 in rat neurons: A controller of membrane rSK2? Frontiers in Neural Circuits, 13, 21. doi: 10.3389/fncir.2019.00021


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