SSPSPredictor: A Sequence- and Structure-Based Deep Learning Model for Predicting Phase-Separating Proteins

Liquid-liquid phase separation (LLPS) underlies the formation of biomolecular liquid condensates (also termed membraneless organelles, MLOs), which are essential for spatially organizing various biochemical processes within cells. Proteins that play a key role in driving condensate formation are termed phase-separating proteins (PSPs). Given that experimental identification of PSPs remains labor-intensive and time-consuming, multiple computational tools have been developed based on empirical features or deep learning. In this study, we propose SSPSPredictor, a novel multimodal predictive model for PSPs with folded or intrinsically disordered structures, leveraging the fusion of sequence information from a protein language model ESM-2 and structural insights from a graph neural network GVP. Compared with existing tools, SSPSPredictor achieves a balanced performance in identifying PSPs, predicting relative LLPS propensities, and recognizing key regions that drive LLPS. More importantly, SSPSPredictor exhibits good interpretability in identifying driving regions along protein sequences, although no relevant supervision was provided during training. Further predictive analysis of the human proteome using SSPSPredictor reveals that the proportion of intrinsically disordered proteins (IDPs) undergoing LLPS is significantly higher than that of the folded proteins. In addition, pathogenic variants, especially those located in disordered regions, exhibit a higher LLPS propensity than other mutations, uncovering a link between LLPS and diseases at the amino acid level. An online Web server for SSPSPredictor (https://bio-comp.ucas.ac.cn/SSPSPredictor/) and its source code (https://github.com/ucas-biocomp/SSPSPredictor) are available.