Ubiquitin specific peptidase 44 (USP44)

Ubiquitin specific peptidase 44 (USP44) is a cysteine protease of the deubiquitinating enzyme (DUB) class, specifically within the ubiquitin-specific protease family[1][2]. USP44 hydrolyzes ubiquitin from specific substrate proteins to regulate their degradation, localization, and activity. It is a critical mitotic checkpoint regulator, chiefly by deubiquitinating CDC20 to prevent premature activation of the anaphase-promoting complex/cyclosome (APC/C), ensuring proper chromosome segregation[1][3][4][8]. USP44 is also involved in DNA repair, by stabilizing proteins at double-strand breaks, and in immune response, stabilizing FOXP3 in regulatory T-cells and modulating STING during DNA virus infections[10][11]. USP44 acts as a context-dependent tumor suppressor or promoter in human cancers; loss or misregulation contributes to chromosomal instability, tumorigenesis, and altered immune function[5]. No approved drugs currently target USP44 directly, but its pivotal roles in cell cycle control and cancer progression highlight its therapeutic relevance.

Other names

Ubiquitin carboxyl-terminal hydrolase 44FLJ14528Deubiquitinating enzyme 44Ubiquitin thioesterase 44Ubiquitin-specific-processing protease 44ubiquitin specific protease 44ubiquitin thiolesterase 44

Deubiquitination of target substrates, mainly lysine-48–linked polyubiquitin chains, stabilization of checkpoint and regulatory proteins (e.g., CDC20, FOXP3, DDB2, Itch), regulation of protein degradation and signal transduction pathways[1][2][10][11].