Abstract: Objective To study the role of LNX1 in the ubiquitination of PBK, a reported LNX1 interactor. Methods A series of recombinant human LNX1 truncations and full-length LNX1 proteins were cloned, bacterial expressed, and purified. In vitro ubiquitination system was used to study the ubiquitination of PBK by LNX1. The ubiquitination and degradation of exogenous PBK was studied in mammalian cells. Results LNX1 promoted the ubiquitination of PBK in in vitro ubiquitination system and the impact of LNX1 truncations to the ubiquitination of PBK was also studied. LNX1 promoted the ubiquitination of exogenous PBK in mammalian cells, leading to its proteasome dependent degradation. Conclusion This research found that ubiquitin ligase LNX1 promotes the ubiquitination and degradation of exogenous PBK, which provides important clues for study the physiologic function of LNX1.

Key words: Ubiquitin Ligase, ubiquitination, LNX1, PBK