Fig. 3. Schematic representation of the structure of mucin-2 (MUC2): the N-terminus is followed by four von Willebrand domains (4-WD, blue hexagons) and two rich cysteine domains (CysD, green circles) with numerous disulphide bonds. The central region shows the first Ser/Thr/Pro rich 21 repetitive region with an irregular amino acid sequence (PTS, pink circles), and the second regular tandemly repeated motifs of 23 amino acids with variable number of tandem repeats from 51 to 115 (VNTR, pink circles). The Ser/Thr/Pro rich series form two highly glycosylated regions upstream the C-terminus, with three von Willebrand domains (3-WD, blue hexagons) and the cysteine knot (CK).