Reply To Verdugo: Mucins Form Highly Organized Supramolecular Structures

The model of mucins as enormously large linear polymers with limited organization has dominated the mucus field. Twenty-five years ago, Verdugo et al. (1) suggested that the mucins are stored as such in the regulated secretory pathway of goblet cells and packed by calcium ions shielding the negative charges (sialic acid and sulfate groups) of the highly glycosylated mucin domains (1, 2). That Ca2+ and low pH are necessary for packing mucins is not controversial, as this is the case for all cell types with regulated secretory machinery. Typical for such granulae, including goblet cells, as shown by Tetsuji et al. (3 …