Figure 8.

A Model of DRIP1 and DRIP2 Functioning in Dehydration Stress Signaling by Targeting DREB2A Degradation.

Under normal growth conditions, the DREB2A protein is expressed at low levels. To prevent the activation of a stress response in the absence of drought conditions, this protein is recognized and ubiquitinated by DRIP1 and DRIP2 protein and subjected to 26S proteasome proteolysis. Under stress, it is possible that the ubiquitination and proteolysis process is either blocked directly by stress-dependent signals or blocked via competition of a stress signal–dependent modification of DREB2A, indicated as question marks in circles. Thus, in drought conditions, plants are able to acquire a sufficient amount of effective DREB2A protein to activate downstream gene expression and produce a stress response.