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carboxyl-terminal domain of ubiquitin-specific protease 25 (USP25) This subfamily contains the C-terminal domain of ubiquitin-specific protease USP25, 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 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. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",