Insulin reduction by Grx-like proteins. Insulin reduction was measured in the presence of DTT and 2 μM poplar Trxh1 (used a control), TmGrx2 and TmGrx3 and 5 μM TmGrx1, by measuring the turbidity at 650 nm caused by the precipitation of reduced insulin. Each trace is a representative experiment, selected from two to three replicates. DTT, dithiothreitol; Trx, thioredoxin.