Receptor-interacting protein kinase-3 (RIP3 or RIPK3) interacts with pellino E3 ubiquitin protein ligase 1 (PELI1) through its forkhead-associated (FHA) domain to mediate K48-linked polyubiquitination of RIPK3 (Choi SW et al. 2018). Mass spectrometric analysis identified K363 of RIPK3 as the main target for PELI1-mediated ubiquitination. In vitro ubiquitination assay showed that PELI1 utilized the ubiquitin-conjugating enzyme UbcH5a to ubiquitinate RIPK3. Proteasome inhibitors (MG132 and BTZ), but not lysosome inhibitors, prevented PELI1-facilitated degradation of stably expressed RIPK3 in HeLa cells and endogenous RIPK3 in HT-29 cells, suggesting that PELI1 controls RIP3 protein destabilization via ubiquitylation-dependent proteasome-mediated degradation (Choi SW et al. 2018). Phosphorylation of RIPK3 at T182 was necessary for PELI1 recruitment and K48-linked polyubiquitination. PELI1-mediated RIPK3 degradation abolished the phosphorylation of mixed lineage kinase domain like pseudokinase (MLKL) and necroptotic cell death in human colorectal adenocarcinoma (HT29) cells, human neonatal epidermal keratinocytes (HEKn), and in lung tissues from PELI1 transgenic mice (Choi SW et al. 2018).
ubiquitin protein ligase activity of p-S-RIPK1:p-S199,227-RIPK3:PELI1 [cytosol]