Schematic structures of MUC7 (A) and MUC5B (B), and epitopes recognized by anti-MUC7 and anti-MUC5B antibodies.

MUC7 and MUC5B are heavily glycosylated by oligosaccharide side chains. Positions of putative N- and O-glycosylation sites, and C-mannosylation sites are marked. O-linked sugars possess terminally located sialic acid residues that were omitted for simplicity. EU-MUC7a, a mouse monoclonal antibody recognizes the amino acid sequence EGRERDHELRHRRHHHQ, located in the N-terminal domain (amino acids 21–37) of MUC7. EU-MUC5Bb (IgG1 subclass) is a mouse monoclonal antibody which recognizes amino acid sequence RNREQVGKFKMC, located in four of the cysteine-rich domains of the tandem repeat of MUC5B (amino acids 2388–2399, 2917–2928, 3615–3626, 4144–4155). The figures were drawn based on the information in Uniprot (accession number Q9HC84 and Q8TAX7).