Jun activation domain-binding protein 1 (JAB1)

Jun activation domain-binding protein 1 (JAB1), also known as COP9 signalosome complex subunit 5 (CSN5), is a multifunctional protein that is a central component of the COP9 signalosome complex. It acts as a deneddylase, removing the ubiquitin-like modifier NEDD8 from Cullin family scaffold proteins, thus regulating the activity of Cullin-RING E3 ubiquitin ligases. JAB1 directly interacts with the Jun activation domain, influencing transcription and protein stability. It is essential in regulating protein degradation and stability, especially of receptor proteins such as the interferon receptor, facilitating optimal interferon signaling by limiting receptor proteolysis. JAB1 plays crucial roles in immune regulation, cell signaling, and is implicated in disease processes including cancer and inflammation, generally through its broad control of protein homeostasis and signaling[2]. - Unlike “Transcription factor Jun” (encoded by JUN or c-Jun)[1][3][4][5], JAB1 is not itself a transcription factor but a regulator of various proteins including transcription factors and receptors, through modulation of ubiquitin-proteasome system function.

Other names

COP9 signalosome complex subunit 5 (CSN5)JAB1Jun activation domain-binding protein 1

Regulation of protein stability through COP9 signalosome-mediated deneddylation of Cullin family proteins, stabilization of cytokine/IFN receptors by antagonizing NEDD8 modification and SCF E3 ligase activity[2]