The gastrointestinal tract is lined with a mucus layer that protects against ingested toxins and pathogens from contacting the underlying epithelium. In the colon, the major protein that forms the mucus layer is MUC2, a glycoprotein that creates a protective gel and provides a food source for resident microbiota. Mucus also contain other proteins, including IgG Fc gamma binding protein (FCGBP) that is heavily N-linked glycosylated with no known function. Based on this knowledge gap, FCGBP was studied to explore its role in host defense and epithelial barrier function. Basally, FCGBP was co-ordinately expressed with MUC2 mucin in human goblet-cell like LS174T cells. Both FCGBP and MUC2 were coordinately biosynthesized, packaged, and stored in mucin granules. Secreted mucus contained both MUC2 and FCGBP and the proteins interacted through non-covalent interactions. Wound healing assays revealed that MUC2 and FCGBP were strongly expressed and co-localized at the wound margin, but this pattern was lost in the absence of MUC2. FCGBP expression was decreased in a mouse model of colonic inflammation, suggesting a role for FCGBP in wound healing. LS174T cells with a missense mutation in FCGBP had an altered mucus and cell glycomics profile from WT cells that correlated with increased intracellular stress and tumorgenicity. Even though FCGBP-Mut cells had higher expression and secretion of MUC2, the mucus was more penetrable to microbeads and susceptible to Salmonella enterica infection with increased adhesion, invasion, and cell death as compared to WT cells. In addition to bacterial invasion, the mucus degrading colonic parasite, Entamoeba histolytica (Eh) was also examined to elucidate how FCGBP-MUC2 mucin protein complex was altered and/or degraded. In response to Eh, both MUC2 and FCGBP expression in WT cells were markedly upregulated and degraded by Eh secreted proteinases. The degradation of FCGBP preceded MUC2 cleavage at the C-terminus. FCGBP-Mut cells constitutively secreted mucus was more adherent to Eh associated with high cell death as compared to WT. These results demonstrate that FCGBP is coordinately regulated and expressed with MUC2 mucin to form a protein complex that constitute the structural building blocks of colonic mucus. Alterations in FCGBP by a single missense mutation rendered the mucus layer more penetrable to pathogens associated with cell death, highlighting the importance of FCGBP together with MUC2 to form the protective mucus layer.