Mucin

Mucins are a large family of high molecular weight, heavily glycosylated proteins produced by epithelial tissues in most animals, serving as major components of the mucus that covers and protects epithelial surfaces throughout the body. Structural hallmarks include a protein core rich in tandem repeats (the PTS domain, abundant in proline, threonine, serine) that are heavily modified by O-linked oligosaccharides, giving mucins their gel-forming and protective properties. They are classified into membrane-bound and secreted (gel-forming and soluble) types, with distinct genomic clusters and domain architectures. Mucins play key roles in lubricating and shielding epithelial surfaces from pathogens and particulates, mediating immune responses, and modulating cell signaling. Dysregulation of mucin expression or glycosylation is implicated in various diseases, most notably cancer (e.g., MUC1 and MUC4 as common tumor markers), chronic inflammation, infections, and respiratory illnesses. While some antibodies and therapies target specific mucin proteins in oncology, their ubiquitous expression and essential protective roles remain major therapeutic challenges.

Other names

MucinsMucin proteinsMUC family (includes MUC1, MUC2, MUC4, MUC5AC, MUC5B, MUC6, etc.)

Blocking adhesion of pathogens (barrier function) Modifying cell signaling pathways Some cancer treatments induce immune targeting of mucin epitopes