Table 2.

Post-translational modifications of RIPK3.

Domain	Residuea		PTM	Modifying enzyme	Effect on necroptosis	Proposed mechanism	Ortholog studied	Cell modelb	Mouse model	Recombinant protein	Reference
	Human	Mouse
Kinase	T182	T187	Phosphorylation	Auto	Both ↑ and ↓, net effect unclear	Promotes RIPK3 kinase activity; but also recruits PELI1 which targets RIPK3 for proteasomal degradation	Human	HT29, 293T	No	Yes	[164]
Kinase	S199	S204	Phosphorylation	Auto	↑ Promotes necroptosis	Promotes RIPK3 kinase activity	Human, mouse	MEF, Jurkat, HT29	No	Yes	[87]
Kinase	S227	T231/S232	Phosphorylation	Auto	↑ Promotes necroptosis	Promotes interaction with MLKL	Mouse, human	MEF, Jurkat, HT29	No	Yes	[28, 87]
	S227	T231/S232		CK1α, CK1δ, and CK1ε			Human	HeLa	No	Yes	[181]
	S227	T231/S232	Dephosphorylation	Ppm1b	↓ Restrict necroptosis	Antagonize essential phosphorylation	Human, mouse	293T, L929, HeLa	Yes	Yes	[183]
Kinase	K5	K5	Deubiquitination	A20	↓ Inhibits complex II formation and cell death	A20 deubiquitinate K63-linked ubiquitin chain of RIPK3 at K5, which is required for necrosome formation	Mouse	T cell, MEF	No	No	[184]
Kinase	K55	K56	K48-linked ubiquitination	CHIP	↓ Attenuates necroptosis	Targets RIPK3 for lysosomal degradation	Mouse, human	MEF, L929, HT29	Yes	No	[156]
Kinase	K89	–	K48-linked ubiquitination	CHIP	–	–	–	–	–	–	[156]
Intermediate	K363	–	K48-linked ubiquitination	CHIP	↓ Attenuates necroptosis	Targets RIPK3 for lysosomal degradation	Mouse, human	MEF, L929, HT29	Yes	No	[156]
		–	K48-linked ubiquitination	PELI1	↓ Attenuates necroptosis	Targets RIPK3 for proteasomal degradation	Mouse, human	MEF, HT29	No	No	[164]
Intermediate	K501	–	K48-linked ubiquitination	CHIP	–	–	–	–	–	–	[156]
Intermediate	D328	D333	Cleavage	Casp8	↓ Inhibits necroptosis	Protease cleavage	Human	HeLa, 293T	No	Yes	[36, 171]
RHIM	N462	Y453	Cleavage	EspL	↓ (Pathogen) inhibits necroptosis	Protease cleavage	Mouse	MDF, BMDM	Yes	Yes	[17]
RHIM	T467	Unknown	O-GlcNAc	OGT	↓ Attenuates necroptosis	Steric hinderance prevent RHIM-mediated RIPK1-RIPK3 interaction	Human, mouse	293T, L929, THP-1, BMDM	Yes	No	[185]

^aEquivalent residues in human and mouse orthologs are inferred by sequence homology. Bold indicates the ortholog residue with direct evidence of such post-translational modification.

^bCell line abbreviations: HT29 human adenocarcinoma cells, 293T human embryonic kidney cell line HEK293T, MEF mouse embryonic fibroblasts, Jurkat human T lymphocyte Jurkat cells, HeLa human adenocarcinoma cells, L292 mouse fibrosarcoma cells, BMDM bone marrow-derived macrophages, THP-1 human monocyte-like cells.