DMBT1 protein (deleted in malignant brain tumors 1 protein, glycoprotein 340, Gp-340, surfactant pulmonary-associated D-binding protein, DMBT1, GP340)

Function

• tumor suppressor gene
  • brain cancer, lung cancer, esophageal cancer, gastric cancer, colorectal cancer
• mucosal defense system (putative)
• cellular immune defense (putative)
• epithelial differentiation
• opsonin receptor or SFTPD & SPAR in macrophage tissues (putative)
• liver regeneration (putative)
• binding protein in saliva for the regulation of taste sensation (putative)
• binds SFTPD & SPAR (Ca+2-dependent)

Compartment

• secreted
• some isoforms may be membrane-bound
• lumenal aspect of crypt cells in small intestine
• lumenal aspect of surface epithelial cells (colon)
• formed in the ducts of von Ebner gland, & released into the fluid bathing the taste buds contained in taste papillae

Alternative splicing

named isoforms=5

Expression

• highly expressed in alveolar & macrophage tissues.
• expressed in lung, trachea, salivary gland, small intestine, stomach
• expressed in certain cells of islets of Langerhans
• expressed at highest levels in lung & small intestine
• expressed in fetal lung, intestine & skin
• secreted to the extracellular matrix (ECM) in certain fetal epithelia
• induced by in intestinal epithelial cells in response to proinflammatory stimuli including TNF-alpha & LPS

Pathology

• allelic loss found in gliomas
  • 25% of medulloblastomas
  • 59% of glioblastomas
• loss or reduction of DMBT1 expression associated with
  • esophageal carcinoma
  • gastric carcinoma
  • lung carcinoma
  • colorectal carcinomas
• a deletion allele of DMBT1 which lacks 5 SRCR domains is associated with an increased risk of Crohn disease

Genetics

• derived from same gene as GP340 which binds lung surfactant protein D

Polymorphism

• the number of SRCR & SRCR-interspersed domains is polymorphic in a variety of tumors & may represent the major site of alterations in cancer

More general terms

• scavenger receptor cysteine-rich (SRCR) superfamily protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1755
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1755
• OMIM: https://mirror.omim.org/entry/137800
• OMIM: https://mirror.omim.org/entry/601969
• UniProt: http://www.uniprot.org/uniprot/Q9UGM3.html