Gate expectations

摘要

The opening and closing ― gating ― of ion channels in response to specific stimuli is crucial for cell function. The membrane-partitioning activities of two venom toxins qive insights into the mechanisms involved. The membrane surrounding a biologi-cal cell forms a highly selective barrier that allows the cell to control its internal environment. It consists of an assembly of lipids and proteins. Some membrane proteins form channels through which ions can flow. These ion channels are said to be 'gated' if they can be opened and closed, and the trigger for this can be electrical, chemical or mechanical stimuli. Ion channels are widely distributed throughout the human body, and in many cells different types of channel coexist. It is their interplay that tunes the cell's electrical activity, enabling it to function properly; even small changes in the balance of activity of the channel proteins can have significant physiological consequences, sometimes leading to severe medical conditions. The development of therapeutic agents that target ion channels is therefore under way.