功能 |
Hydrolase that can remove conjugated ubiquitin from proteins and therefore plays an important regulatory role at the level of protein turnover by preventing degradation. Converts both 'Lys-48' an 'Lys-63'-linked ubiquitin chains. Catalytic activity is enhanced in the M phase. Involved in cell proliferation. Required to enter into S phase in response to serum stimulation. May regulate T-cell anergy mediated by RNF128 via the formation of a complex containing RNF128 and OTUB1. Probably regulates the stability of STAM2 and RASGRF1. Regulates endosomal ubiquitin dynamics, cargo sorting, membrane traffic at early endosomes, and maintenance of ESCRT-0 stability. The level of protein ubiquitination on endosomes is essential for maintaining the morphology of the organelle. Deubiquitinates EPS15 and controles tyrosine kinase stability. Removes conjugated ubiquitin from EGFR thus regulating EGFR degradation and downstream MAPK signaling. Involved in acrosome biogenesis through interaction with the spermatid ESCRT-0 complex and microtubules. Deubiquitinates BIRC6/bruce and KIF23/MKLP1.
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總結(jié) |
Ubiquitinating enzymes (UBEs) catalyze protein ubiquitination, a reversible process countered by deubiquitinating enzyme (DUB) action. Five DUB subfamilies are recognized, including the USP, UCH, OTU, MJD, and JAMM enzymes. The deubiquitinating enzyme ubiquitin-specific protease 8 (USP8/UBPy) is a cysteine protease belonging to the USP/UBP subfamily. Research studies have shown that USP8 is an essential growth-regulated enzyme indispensible for cell proliferation and survival. Indeed, conditional knock-out of murine USP8 was shown to promote a dramatic loss in expression of receptor tyrosine kinases, including EGFR, ErbB3, and c-Met. In agreement with these findings, USP8 inactivation leads to enhanced ubiquitination of ligand-activated EGFR. Furthermore, phosphorylation of USP8 at Ser680 results in its binding of 14-3-3, catalytic inactivation, and reduced EGFR deubiquitination. It appears as though USP8, in conjunction with components of the ESCRT-0 complex, plays an integral role in the early endosomal sorting machinery that functions to protect EGFR from lysosomal degradation.
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