Ubiquitin Specific Peptidase 4 (USP4)

Using Western blots, Gupta et al. (1994) found that Unp has an apparent molecular mass of 180 kD and is located in the nuclear fraction of mammalian cell extracts. They reported that overexpression of Unp led to oncogenic transformation of NIH 3T3 cells injected into athymic mice. The ubiquitin-specific proteases (UBPs) are a group of deubiquitinating enzymes that possess 2 signature motifs, the Cys box and the His box. By screening a human frontal cortex library with a Unp cDNA, Gray et al. (1995) isolated cDNAs encoding human UNP, or UNPH. The predicted protein contained both conserved UBP domains. Northern blot analysis of primary lung tumor samples indicated that levels of UNP mRNA were elevated in small cell carcinomas and adenocarcinomas relative to normal adult lung.