Phospho-A20/TNFAIP3 (Ser381) Antibody #63523

A20, also referred to as TNF-α-induced protein 3 (TNFAIP3), is cytokine-inducible protein that functions to inhibit apoptosis and activate NF-κB (1,2). It was first identified as a TNF-α inducible primary response gene in human umbilical vein endothelial cells, and encodes a 790-amino acid protein containing seven Cys2/Cys2-zinc finger motifs (3). Constitutive expression of A20 is observed in lymphoid tissues (4), but it is transiently expressed in a variety of cell types in response to inflammatory signals such as TNF-α (3,5), IL-1 (3,5), phorbol esters (6), and LPS (7). Expression of A20 can confer resistance to apoptosis and NF-κB activation triggered by these signals, probably through interference with TRAF (TNF receptor associated factor) family members (8,9), and interaction with the NF-κB inhibiting protein ABIN (10). Studies also show that A20 contains site-specific ubiquitin modifying activity that can contribute to its biological functions (11,12). The amino-terminus of A20 contains de-ubiquitinating (DUB) activity for Lys63 branches, such as those found in TRAF6 and RIP, while the carboxyl-terminus contains ubiquitin ligase (E3) activity for Lys48 branches of the same substrates and leads to their degradation (12).
A20 gets phosphorylated at Ser381 by IKKβ downstream of various innate immune activators, which enhances the deubiquitnase activiaty of A20 leading to disassembly of inflammatory signaling complexes (13). Therefore, A20 works as part of a negative feedback loop to limit NF-κB activation and inflammatory signaling (13). Phosphorylation at Ser381 could be used as a marker of active A20.