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Updated: Aug 29, 2026

In-vitro Reconstitution of Bacterial Ubiquitination and VCP/p97-mediated Elimination
Published on: January 2, 2026
NIRF is a ubiquitin ligase that is capable of ubiquitinating PCNP, a PEST-containing nuclear protein
Tsutomu Mori1, Yuanyuan Li, Hiroaki Hata
1Department of Biochemistry, Fukushima Medical University, School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan.
Abstract:
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.
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