Jab1CSN5

Jab1CSN5, also known as JAB1 or CSN5, is a protein encoded by the COPS5 gene in humans. It is a subunit of the COP9 signalosome, a multi-protein complex that plays a crucial role in regulating the stability and activity of various proteins, particularly those involved in cell cycle progression, DNA repair, and signal transduction.

The COP9 signalosome is conserved across eukaryotes and functions as a molecular switch, modulating protein degradation pathways mediated by the ubiquitin-proteasome system. Jab1CSN5, specifically, interacts with and regulates the activity of CUL4-DDB1-ROC1 E3 ubiquitin ligase complexes, which target proteins for degradation. This regulation is critical for maintaining cellular homeostasis and preventing uncontrolled cell growth.

Dysregulation of Jab1CSN5 has been implicated in the development and progression of several diseases, including cancer. Its role in controlling protein stability means that altered Jab1CSN5 activity can lead to the accumulation of oncogenic proteins or the premature degradation of tumor suppressor proteins, thereby promoting tumorigenesis. Research into Jab1CSN5's functions continues to explore its potential as a therapeutic target for various cancers and other diseases.