Related Experiment Video
Updated: May 12, 2026

In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Dimerization and ubiquitin mediated recruitment of A20, a complex deubiquitinating enzyme
Timothy T Lu1, Michio Onizawa, Gianna E Hammer
1Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-0451, USA.
Abstract:
A20 is an anti-inflammatory protein linked to multiple human autoimmune diseases and lymphomas. A20 possesses a deubiquitinating motif and a zinc finger, ZF4, that binds ubiquitin and supports its E3 ubiquitin ligase activity. To understand how these activities mediate A20's physiological functions, we generated two lines of gene-targeted mice, abrogating either A20's deubiquitinating activity (Tnfaip3(OTU) mice) or A20's ZF4 (Tnfaip3(ZF4) mice). Both Tnfaip3(OTU) and Tnfaip3(ZF4) mice exhibited increased responses to TNF and sensitivity to colitis. A20's C103 deubiquitinating motif restricted both K48- and K63-linked ubiquitination of receptor interacting protein 1 (RIP1). A20's ZF4 was required for recruiting A20 to ubiquitinated RIP1. A20(OTU) proteins and A20(ZF4) proteins complemented each other to regulate RIP1 ubiquitination and NFκB signaling normally in compound mutant Tnfaip3(OTU/ZF4) cells. This complementation involved homodimerization of A20 proteins, and we have defined an extensive dimerization interface in A20. These studies reveal how A20 proteins collaborate to restrict TNF signaling.
Related Concept Videos
The Proteasome
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
The Proteasome
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
Regulated Protein Degradation
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Regulated Protein Degradation
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Export of Misfolded Proteins out of the ER
Anaphase Promoting Complex

