mucin-2; MUC-2; intestinal mucin-2 (MUC2, SMUC)

Function

• coats epithelia of the intestines, airways, & other mucus membrane-containing organs
• thought to provide a protective, lubricating barrier against particles & infectious agents at mucosal surfaces
• major constituent of both the inner & outer mucus layers of the colon & may play a role in excluding bacteria from the inner mucus layer
• may undergo proteolytic cleavage in the outer mucus layer of the colon, contributing to the expanded volume & loose nature of this layer which allows for bacterial colonization in contrast to the inner mucus layer which is dense & devoid of bacteria
• at low pH of 6 & under, undergoes autocatalytic cleavage in vitro in the N-terminal region of the fourth VWD domain; it is likely that this also occurs in vivo & is triggered by the low pH of the late secretory pathway
• dimerizes in the endoplasmic reticulum via its C-terminal region & polymerizes via its N-terminal region by disulfide-linked trimerization
• interacts with FCGBP

Structure

• homotrimer; disulfide-linked
• O-glycosylated
• contains 1 CTCK (C-terminal cystine knot-like) domain
• contains 1 TIL (trypsin inhibitory-like) domain
• contains 2 VWFC domains
• contains 4 VWFD domains

Compartment

• secreted
• in the intestine, secreted into the inner & outer mucus layers (putative)

Expression

• colon, small intestine, colonic tumors, bronchus, cervix & gall bladder

Polymorphism

• the number of repeats is highly polymorphic & varies among different alleles

More general terms

• mucin
• secreted protein
• phosphoprotein

Database

• UniProt: http://www.uniprot.org/uniprot/Q02817.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=4583
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:4583
• OMIM: https://mirror.omim.org/entry/158370