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mucin-5AC; mucin-5 subtype AC, tracheobronchial; tracheobronchial mucin; TBM; major airway glycoprotein; gastric mucin; Lewis B blood group antigen; LeB (MUC5AC, MUC5)
Function:
- gel-forming glycoprotein of gastric & respiratory tract epithelia that protects the mucosa from infection & chemical damage by binding to inhaled microrganisms & particules that are subsequently removed by the mucocilary system
- may be required for proper folding of these regions & for export from the endoplasmic reticulum during biosynthesis
- proteolytic cleavage in the C-terminal is initiated early in the secretory pathway & does not involve a serine protease
- extent of cleavage is increased in the acidic parts of the secretory pathway
- cleavage generates a reactive group which could link MUC5AC to a primary amide
- interacts with H pylori in the gastric epithelium, Barrett's esophagus as well as in gastric metaplasia of the duodenum
Structure:
- multimeric
- S-, O- & N-glycosylated
- O-glycosylated on the Thr-/Ser-rich tandem repeats
- S-mannosylation in the Cys-rich subdomains
- the Cys in the Cys-rich subdomain repeats are not involved in disulfide bonding
- contains 1 CTCK (C-terminal cystine knot-like) domain
- contains 2 VWFC domains
- contains 4 VWFD domains
Compartment: secreted
Expression:
- highly expressed in surface mucosal cells of respiratory tract & stomach epithelia
- overexpressed in a number of carcinomas
- expressed in Barrett's esophagus epithelium & in the proximal duodenum
General
mucin
secreted protein
Properties
SIZE: entity length = 5030 aa
MW = 527 kD
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-27}
VWFD domain {80-281}
MOTIF: cysteine residue {C103}
MODIFICATION: cysteine residue {C111}
cysteine residue {C111}
MODIFICATION: cysteine residue {C103}
N-glycosylation site {N205}
N-glycosylation site {N258}
N-glycosylation site {N415}
VWFD domain {433-647}
MOTIF: cysteine residue {C456}
MODIFICATION: cysteine residue {C464}
cysteine residue {C464}
MODIFICATION: cysteine residue {C456}
N-glycosylation site {N524}
VWFD domain {902-1109}
peptide motif {1193-1195}
N-glycosylation site {N1308}
domain {1383-4107}
MOTIF: Cys-rich {1383-1481}
Cys-rich {1577-1677}
Cys-rich {1743-1847}
Cys-rich {1950-2050}
Cys-rich {2116-2220}
TTSTTSAP repeats {2257-2624}
Cys-rich {2646-2750}
TTSTTSAP repeats {2787-2922}
Cys-rich {2944-3084}
TTSTTSAP repeats {3085-3355}
N-glycosylation site {N3198}
Cys-rich {3377-3481}
TTSTTSAP repeats {3517-3971}
Cys-rich {4003-4107}
N-glycosylation site {N4245}
VWFD domain {4296-4507}
MOTIF: peptide motif {4302-4303}
N-glycosylation site {N4318}
N-glycosylation site {N4433}
N-glycosylation site {N4469}
N-glycosylation site {N4612}
VWFC domain {4652-4721}
N-glycosylation site {N4723}
N-glycosylation site {N4753}
VWFC domain {4757-4824}
MOTIF: N-glycosylation site {N4762}
N-glycosylation site {N4831}
proline-rich region
SITE: 4896-4901
MOTIF: proline residue (SEVERAL)
N-glycosylation site {N4904}
C-terminal cystine knot {4908-4996}
MOTIF: cysteine residue {C4908}
MODIFICATION: cysteine residue {C4958}
cysteine residue {C4922}
MODIFICATION: cysteine residue {C4972}
cysteine residue {C4933}
MODIFICATION: cysteine residue {C4988}
cysteine residue {C4937}
MODIFICATION: cysteine residue {C4990}
cysteine residue {C4958}
MODIFICATION: cysteine residue {C4908}
N-glycosylation site {N4967}
cysteine residue {C4972}
MODIFICATION: cysteine residue {C4922}
cysteine residue {C4988}
MODIFICATION: cysteine residue {C4933}
cysteine residue {C4990}
MODIFICATION: cysteine residue {C4937}
Database Correlations
OMIM 158373
UniProt P98088
PFAM correlations
References
- UniProt :accession P98088
- mucin database
http://www.medkem.gu.se/mucinbiology/databases/