Mucin-17 is a protein that in humans is encoded by the MUC17 gene. Membrane mucins, such as MUC17, function in epithelial cells to provide cytoprotection, maintain luminal structure, provide signal transduction, and confer antiadhesive properties upon cancer cells that lose their apical/basal polarization. MUC17, contains an extended, repetitive extracellular glycosylation domain and a carboxyl terminus with two EGF-like domains, a SEA module domain, a transmembrane domain, and a cytoplasmic domain with potential serine and tyrosine phosphorylation sites. Interacts via its C-terminus with PDZK1 and this interaction appears important for proper localization.