Ins and outs of nerve ion channel interactions revealed
Researchers from the University of Pennsylvania have discovered the mechanism that allows ion channels to work in pairs to control electrical signals in neurons. The channels are coupled by a connecting protein.
Ion channels are pores in the cell membrane made up of proteins, which act like tiny sluices and only allow certain charged atoms, such as potassium, calcium or sodium, through into the body cells. The channels are triggered to open and close the gates by electrical signals in the cell envelope or through messenger substances that can dock at certain points on the surface of the cell envelope. Many diseases of the nervous system - for example epilepsies - are based on defective ion channels.
As Edward Cooper and colleagues found out in a series of experiments, both sodium and potassium ion channels connect to the protein ankyrin-B with identical binding sites. This protein in turn anchors the two to the framework of the nerve cell and mediates the coordinated opening and closing of the ion channels. Coordination is critical to the transmission, timing, and patterns of nerve impulses.
The researchers also report that the common docking site for ankyrin-B ion channels is only found in vertebrates. This could be the reason for the higher performance of their brains, they suspect.