USP44

Deubiquitinase that plays a key regulatory role in the spindle assembly checkpoint or mitotic checkpoint by preventing premature anaphase onset. Acts by specifically mediating deubiquitination of CDC20, a negative regulator of the anaphase promoting complex/cyclosome (APC/C). Deubiquitination of CDC20 leads to stabilize the MAD2L1-CDC20-APC/C ternary complex (also named mitotic checkpoint complex), thereby preventing premature activation of the APC/C. Promotes association of MAD2L1 with CDC20 and reinforces the spindle assembly checkpoint. Also promotes the deubiquitination of histone H2A and H2B. Recruited to RNF8/RNF168-ubiquitinated chromatin surrounding double stranded breaks (DSBs), promotes hydrolysis of such ubiquitin conjugates, thus negatively regulating protein recruitment to damaged chromatin. Participates in nucleotide excision repair (NER) pathway by deubiquitinating DDB2 to prevent its premature degradation so it can remain on damaged chromatin (By similarity). Promotes FOXP3 stabilization through 'Lys-48'-linked deubiquitination leading to increased stability and increased regulatory T-cell lineage stability. Also plays a positive role in innate immune response to DNA viruses by deubiquitinating STING1, selectively removing its 'Lys-48'-linked polyubiquitin chains and stabilizing it..

Function from UniProtKB (Q9H0E7), read 2026-09-23. CC BY 4.0.