E3 ubiquitin-protein ligase involved in the regulation of protein import in the chloroplast. Associates with TOC complexes and mediates ubiquitination of TOC components, promoting their degradation via the ubiquitin-proteasome system (UPS). Plays a role in the reorganization of the TOC machinery. Involved in a mechanism that regulates plastid biogenesis via UPS (PubMed:23118188). Promotes stress tolerance by depleting the chloroplast protein import apparatus, which limits photosystem assembly and the potential for reactive oxygen species (ROS) formation (PubMed:26387714). May act as negative regulator of programmed cell death (PCD) during biotic stress (PubMed:20972793). S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with TOC33, TOC75-3 and TOC159. A number of isoforms are produced. According to EST sequences. By infection with the bacterial pathogen Pseudomonas syringae pv. tomato, and treatment with fumonisin B1, a mycotoxin inducing apoptosis-like programmed cell death (PCD). The zinc finger domain is required for E3 ligase activity. Auto-ubiquitinated. No visible phenotype under normal growth conditions, but mutant plants show increased disease symptoms and cell death after inoculation with an avirulent strain of Pseudomonas syringae pv. tomato DC3000 (PubMed:20972793). Pale-green phenotype with low survival rates during de-etiolation (PubMed:23118188). Hypersensitivity to salt, osmotic, and oxidative stresses (PubMed:26387714). Was originally thought to correspond to two different genes At1g63890 and At1g63900. Was originally thought to correspond to two different genes At1g63890 and At1g63900.