mucin structure as chemical glycosylated proteins closeup outline diagram

mucin structure protein anatomical glycans barrier mucus biology cell chemical gastric gastrointestinal health anatomy digestion medicine microscope science small diagram info scientific stomach illustration graphic vector microsdcopic snails gel lubricant epithelial tissues secretion outline labeled educational explanation core transmembrane cytomplasmic region animal mollusks gene carbohydrates muc parts glycosylated glycosylation