FIGURE 1.

Function of E3 ligases in abiotic stress response. (A) Most common type of plant E3s. Ubiquitin ligases are categorized based on the presence of a RING, HECT, or U-box E2-binding domain. RING and U-box domain-containing E3s mediate transfer of ubiquitin (U) directly from the E2-Ub intermediate to the substrate protein. HECT domain-containing E3s form an E3-Ub intermediate prior to the transfer of ubiquitin to the substrate protein. RING domains are found in monomeric E3s and multisubunit CRLs. (B) Illustrations of the most common modes of action for E3 ligases in regulating abiotic stress responses. (1) E3 ligases may function as a negative response regulators required to supress stress response pathways by targeting positive regulators for degradation. (2) E3 ligases may promote stress signaling by functioning as positive response regulators that target negative regulators for degradation following stress perception. (3) E3 ligases may also function to attenuate stress signaling by targeting positive regulators for degradation.