NIRF is a ubiquitin ligase that is capable of ubiquitinating PCNP, a PEST-containing nuclear protein.
We previously reported the association of a novel Np95/ICBP90-like RING finger protein (NIRF) with a novel PEST-containing nuclear protein (PCNP). NIRF is a nuclear protein with a ubiquitin-like domain, a PHD finger, a YDG/SRA domain, Rb-binding motifs and a RING finger. In this study, we showed that NIRF has auto-ubiquitination activity, the hallmark of a ubiquitin ligase. PCNP was readily ubiquitinated in 293 and COS-7 cells, and NIRF ubiquitinated PCNP in vitro as well as in vivo. Considering that NIRF is implicated in cell cycle regulation, these findings suggest that NIRF and PCNP are a ubiquitin ligase and its substrate, respectively, and may constitute a novel signaling pathway with some relation to cell proliferation.
Mori
Tsutomu
T
Department of Biochemistry, Fukushima Medical University, School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan.
Li
Yuanyuan
Y
Hata
Hiroaki
H
Kochi
Hideo
H
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019556:COS Cells; D002384:Catalysis; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011817:Rabbits; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D009687:Nuclear Proteins; C465618:PCNP protein, human; D025801:Ubiquitin; C465619:UHRF2 protein, human; D044767:Ubiquitin-Protein Ligases