May function as a ubiquitin-protein or polyubiquitin hydrolase involved both in the processing of ubiquitin precursors and of ubiquitinated proteins. May therefore play an important role regulatory role at the level of protein turnover by preventing degradation of proteins through the removal of conjugated ubiquitin. Essential component of TGF-beta/BMP signaling cascade. Deubiquitinates monoubiquitinated SMAD4, opposing the activity of E3 ubiquitin-protein ligase TRIM33. Monoubiquitination of SMAD4 hampers its ability to form a stable complex with activated SMAD2/3 resulting in inhibition of TGF- beta/BMP signaling cascade. Deubiqitination of SMAD4 by USP9X re- empowers its competence to mediate TGF-beta signaling. USP9Y is located in the 'azoospermia factor a' (AZFa) region on chromosome Y which is deleted in Sertoli cell- only syndrome. This is an infertility disorder in which no germ cells are visible in seminiferous tubules leading to azoospermia. However, AZFa deletions resulting in complete loss of USP9Y have also been found in normospermic men (PubMed:19246359). Defects in USP9Y may be a cause of spermatogenic failure Y-linked type 2 (SPGFY2). It is a disorder resulting in the absence (azoospermia) or reduction (oligozoospermia) of sperm in the semen, leading to male infertility. The role of USP9Y in spermatogenesis failure is uncertain. A 4-bp deletion in a splice-donor site, causing exon skipping and protein truncation has been observed in non-obstructive azoospermia (PubMed:10581029). However, complete USP9Y deletion has been detected in individuals with no spermatogenic defects (PubMed:19246359). Belongs to the peptidase C19 family. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: EC 184.108.40.206; Protease; Ubiquitin conjugating system; Ubiquitin-specific protease