This entry represents the C-terminal domain of ubiquitin-specific protease USP25 from chordata, a deubiquitinase (DUB), which shares high similarity with USP28 but varies in cellular function; USP25 is a regulator of the innate immune system and may play a role in tumorigenesis, while USP28 is known for its tumor-promoting role. USP25 regulates inflammatory TRAF signaling, and USP28 stabilizes c-MYC and other nuclear proteins. These two closely related DUBs contain an N-terminal domain harboring a Ub-associated domain (UBA) and two Ub-interacting motifs (UIMs), a central catalytic USP domain, and a C-terminal region of unknown function and variable size due to alternative splicing. In general, USP catalytic domains are around 350 amino acids in length; however, in USP25 and 28, the catalytic domains span around 550 amino acids due to a large, conserved insertion at a common insertion point called the USP25/28 catalytic domain inserted domain (UCID). This C-terminal region has been implicated in substrate binding for USP25 and harbors the splicing site for isoform-specific sequences. Structure studies show that the C-terminally extended USP25 is exclusively tetrameric [, , , , , , ].
This entry represents the C-terminal domain of ubiquitin-specific protease USP28, a deubiquitinase (DUB), which shares high similarity with USP25 but varies in cellular function [, ]. USP28 is known for its tumor-promoting role while USP25 is a regulator of the innate immune system and may play a role in tumorigenesis [, , , ]. USP28 stabilises c-MYC and other nuclear proteins, and USP25 regulates inflammatory TRAF signalling. These two closely related DUBs contain an N-terminal domain harbouring a Ub-associated domain (UBA) and two Ub-interacting motifs (UIMs), a central catalytic USP domain, and a C-terminal region of unknown function and variable size due to alternative splicing. In general, USP catalytic domains are around 350 amino acids in length; however, in USP25 and 28, the catalytic domains span around 550 amino acids due to a large, conserved insertion at a common insertion point called USP25/28 catalytic domain inserted domain (UCID) [, ].This C-terminal region has been implicated in substrate binding for USP28 and harbours the splicing site for isoform-specific sequences. Structure studies suggest that the C-terminal domain forms an independent entity.
This entry represents the N-terminal ubiquitin-interacting motif (UIM) found in ubiquitin carboxyl-terminal hydrolase 25 and 28, which are ubiquitin-specific proteases (USP) []. This domain provides a structural basis for the recognition and recruitment of ubiquitin substrates, potentially conferring USP display of catalytic activity [].USP25 functions in various biological processes including inflammation, immune response [, ]. It modulates the Wnt/beta-catenin pathway by deubiquitinating and stabilizing tankyrases TNKS1 and TNKS2 [, ]. USP25 regulates KEAP1-NRF2 axis in the defense against oxidative assaults by deubiquitinating KEAP1 and protecting it from degradation leading to degradation of the NRF2 transcription factor that is responsible for mounting an anti-oxidation gene expression program [].USP28 is involved in DNA damage response checkpoint and MYC proto-oncogene stability. Involved in DNA damage induced apoptosis by specifically deubiquitinating proteins of the DNA damage pathway such as CLSPN []. It is also involved in G2 DNA damage checkpoint, by deubiquitinating CLSPN, and preventing its degradation by the anaphase promoting complex/cyclosome (APC/C). In contrast, it does not deubiquitinate PLK1. It deubiquitinates ZNF304, hence preventing ZNF304 degradation by the proteasome and leading to the activated KRAS-mediated promoter hypermethylation and transcriptional silencing of tumor suppressor genes (TSGs) in a subset of colorectal cancers (CRC) cells [].
