An antibody-based method for monitoring in vivo oxidation of protein tyrosine phosphatases

Regulation of protein tyrosine phosphatases (PTPs) through reversible oxidation of the active site cysteine is emerging as a general, yet poorly characterized, mechanism for control of the activity of this important group of enzymes. This regulatory mechanism was initially described after in vitro treatment of PTPs with oxidizing agents. However, accumulating evidence has substantiated the notion that this mechanism is also operating in vivo, e.g., in association with the transient increase in H(2)O(2) production which occurs after activation of receptor tyrosine kinases. A novel generic antibody-based method for monitoring of PTP oxidation is described. The sensitivity of this strategy has been validated by the demonstration of oxidation of endogenously expressed PTPs after stimulation of cells with growth factors. The method was also instrumental in providing the first evidence for intrinsic differences between PTP domains with regard to sensitivity to oxidation.