Protein engineering, a relatively young field, has played a pivotal role in bringing biotechnology to the forefront of academic research and industrial practice. By focusing on the engineering of single target proteins, a great number of value-added natural and unnatural proteins have been successfully generated and commercialized, such as monoclonal antibodies, industrial enzymes, protein pharmaceuticals, etc. Looking forward to solve problems in more complex biological systems, our laboratory aims to engineer protein assemblies consisting of multiple proteins as a single entity to act in an orchestrated and synergistic manner to carry out specific and more sophisticated biological functions, such as immune-modulation and cascade catalysis. To meet our goals, the protein-assembly engineering must be in sync with an in-depth understanding of the biology underpinning individual problems. As such, our research program puts a balanced emphasis on both technology development and fundamental science. The key to our approach is thus highly interdisciplinary and involves state-of-the-art biology, chemistry, immunology, and biostatistics, with protein engineering principles (directed evolution and rational design) serving as the foundation.