Mucin-5AC and Mucin-5B gel-forming proteins (MUC5AC/MUC5B)

Gel-forming mucins, primarily Mucin-5AC (MUC5AC) and Mucin-5B (MUC5B), are large, heavily glycosylated proteins secreted by airway epithelial goblet cells and submucosal glands [1.1.3, 1.3.3]. These proteins polymerize via the formation of extracellular disulfide bonds between cysteine-rich domains, creating a complex, viscoelastic gel network essential for mucociliary clearance and protecting the lungs from pathogens and particulates [1.1.2, 1.1.4]. In chronic airway diseases like cystic fibrosis, asthma, and COPD, hypersecretion and oxidative stress lead to the formation of pathological, highly cross-linked mucus that is difficult to clear [1.1.1, 1.2.3]. Therapeutic strategies target these extracellular disulfide bonds using reducing agents (mucolytics) to break the polymers into smaller subunits, thereby reducing mucus viscosity and improving clearance [1.3.1, 1.1.5].

Other names

Airway mucinsPolymeric mucinsMucin-5ACMucin-5BSecreted gel-forming mucinsMucin disulfide bonds

Reduction of intermolecular disulfide bonds through thiol-disulfide exchange, leading to the depolymerization of mucin networks and a subsequent decrease in mucus viscoelasticity [1.1.1, 1.3.1].