Figure 3.

Oxidoreductive regulation of transglutaminase 2 (TG2) by endogenous thioredoxin-1 (TRX) and ERp57. (A) Two different doses of TG2 were immobilized onto fibronectin-coated 96 well plates. Significant stimulation of low levels of TG2 (0.1 µM) by TRX. Coincubation with ERW1041 at 200-fold molar excess reduced this effect by trend. At higher doses of TG2 (0.4 µM), stimulation by TRX (4 µM) was less pronounced, but enzymatic activity could be reduced up to the background level via oxidation by ERp57. (B) 0.1 µM TG2 was immobilized onto tissue culture-treated 96 well plates. Reduction by dithiothreitol (DTT) resulted in a slightly, not statistically significant enhanced TG2 activity. TRX significantly raised TG2 activity in a dose-dependent manner. Oxidation of TG2 by ERp57 trended to reduce TG2 activity. (C) mTG activity was not significantly influenced by DTT, TRX and ERp57. B) Red line = background signal. B/C) Black dashed line = control condition. Data are shown as mean ± standard deviation. * p < 0.05, ** p < 0.01.