"The channel-like protein binds potassium, at first very specifically and with high affinity, while the pump enables an active transport that can enrich potassium in the cell by 10,000-fold." ...

The alternative to active transport ... Hydrogen pumps build up an electrochemical gradient of H+ ions in cells to power cellular respiration. Transmembrane proteins are proteins that cross ...

This takes place when molecules diffuse across the cell membrane by travelling through specific transport proteins ... concentration with energy: The proteins pump sodium out of the cells and ...