Sci. Signal., 13 December 2011
Cell Biology Better Is Not Always Best
L. Bryan Ray
Science, Science Signaling, AAAS, Washington, DC 20005, USA
Once a cell has evolved a high-affinity transporter for nutrients like phosphate or zinc, why would it need to continue to make low-affinity transporters as well? Levy et al. address this question in yeast and show that the lower-affinity form does come in handy. When nutrients are plentiful, the low-affinity transporter is expressed and works fine. As nutrient concentrations are depleted, the low-affinity transporter begins to lose efficiency and the nutrient influx dips. This signals the cell to begin preparation for starvation—at a time earlier than it would have, if it had waited until nutrient concentrations got so low that function of the high-affinity transporter became compromised. Sensing a decrease in nutrient supply before concentrations get low enough to inhibit growth thus appears to be a key reason for expressing transporters of both low and high affinity.
Citation: L. B. Ray, Better Is Not Always Best. Sci. Signal. 4, ec346 (2011).
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