Monday 31 May 2004
Mucins represent a heterogeneous group of high-glycosylated and high-molecular-weight glycoproteins encoded by several mucin genes clustered on chromosome 11p15.5, basically consisting of a common proteic backbone (apomucin) linked to oligosaccharides.
They are the major structural component of mucus and are widely expressed by most human epithelial tissues.
- MUC2 and MUC5AC represent a subset of gel-forming mucins: the former is an intestinal-type secretory mucin mainly expressed in goblet cells of normal bowel and in intestinal adenocarcinoma, but also in intestinal metaplasia, whereas the latter is mainly observed in surface mucous cells of the gastric mucosa and respiratory epithelium.
The molecular mechanisms required for sensing high osmolarity in the extracellular environment are not well defined in eukaryotes.
Yeast Msb2 and Hkr1, which are related to mammalian mucins, are excellent candidates for sensing osmostress and for activating the HOG stress-activated protein kinase pathway involved in osmostress adaptation.
Transmembrane mucins activate several signaling cascades in mammals and could therefore be important for sensing osmotic imbalances in higher eukaryotes.