A role for ectophosphatase in xenobiotic resistance

Xenobiotic resistance in animals, plants, yeast, and bacteria is known to i nvolve ATP binding cassette transporters that efflux invading toxins. We pr esent data from yeast and a higher plant indicating that xenobiotic resista nce also involves extracellular ATP degradation. Transgenic upregulation of ecto-ATPase alone confers resistance to organisms that have had no previou s exposure to toxins. Similarly, cells that are deficient in extracellular ATPase activity are more sensitive to xenobiotics. On the basis of these an d other supporting data, we hypothesize that the hydrolysis of extracellula r ATP by phosphatases and ATPases may be necessary for the resistance confe rred by P-glycoprotein.