Protein-protein interactions (PPIs) form the molecular foundation of cellular life. Over the past two decades, computational methods for PPI analysis have primarily focused on prediction—inferring interaction properties from protein information. However, a notable conceptual shift is underway away from predictive analysis and toward rational protein interaction design. This transformation is driven by breakthroughs in protein language models, diffusion models, and equivariant neural networks. In this review, we discuss how this transition represents a notable conceptual shift, enabling exploration of sequence-structure space that evolution has never sampled. We synthesize the technical foundations, core design tasks, and challenges ahead. We address critical issues including evaluation bias, the hallucination problem, and dual-use considerations. We conclude with grand challenges for the field: mapping design ability boundaries, designing dynamic interactions, and developing interpretable methods for clinical translation. We further describe how modern AI reshapes computational approaches for biological discovery.




