Screening and optimizing conditions for crystallization of human recombinant proteins participants in post-translational modifications

The association between the two proteins Nuclear protein localization protein 4 and Ubiquitin recognition factor in ER Associated Degradation 1, abbreviated as (hNpl4- Ufd1), which is specific to the human ubiquitin-proteasome system, plays an important role in many aspects of cellular functions, including cell replication, protein degradation, and protein transport. The structure and function of these proteins (Npl4-Ufd1) have been detailed in numerous studies. Although much interest has been raised about the structure and function of Npl4-Ufd1 from the past to date, only a study by Nguyen et al. (2022) described the detailed structure of this complex protein in humans. The study also shows that the screening and crystallization process plays an important role, having a decisive influence on the quality of the observation and structural analysis of hNpl4-Ufd1. In this study, we want to present the process of finding out the conditions to create single and complex crystals of two proteins Ufd1 - Npl4, and then optimizing the environmental conditions to be able to conduct molecular structure analysis using X-ray diffraction.