PROJECT SUMMARY Human liver fibrosis is intimately controlled by noncovalent interactions between Galectin-3 and unknown cell surface glycoproteins on hepatic stellate cells. Here, we seek to develop methodologies to identify these functional glycoproteins. However, glycosylation is a post-translational modification that results in the construction of highly complex and heterogeneous glycan molecules whose structures are challenging to predict based on the genetic code alone. Despite significant advances in glycoscience, achieving selective control over biological events mediated by glycans and GBPs remains a significant obstacle. At the heart of this problem is the limited resolution with which protein-glycan interactions are analyzed. Glycans are largely displayed as conjugates with proteins, and such protein-glycoprotein interactions provide context for the ensuing biological process. In this application, we propose approaches to identify the interactions between Galectin-3 and glycoproteins in liver stellate cells, and to catalogue the functional consequences resulting from these binding events in the context of human physiology, development, and disease. These approaches integrate techniques in quantitative mass spectrometry, genetics, and glycomics. This work provides novel solutions to a key problem in glycoscience and will open new opportunities for the exploration of glycans for applications in drug discovery and biomedicine.