How cells brace themselves for starvation
Sugar, cholesterol, phosphates, zinc – a healthy body is amazingly good at keeping such vital nutrients at appropriate levels within its cells. From an engineering point of view, one all-purpose model of pump on the surface of a cell should suffice to keep these levels constant: When the concentration of a nutrient, say, sugar, drops inside the cell, the pump mechanism could simply go into higher gear until the sugar levels are back to normal. Yet strangely enough, such cells let in their nutrients using two types of pump: One is active in "good times," when a particular ...



