Small Breast Epithelial Mucin (SBEM)

Small breast epithelial mucin (SBEM) is a recently described gene product that shows promise as a new breast biomarker.Using expression profiling of EST and SAGE databases, Miksicek et al. (2002) identified SBEM, which encodes a putative 90-amino acid protein. SBEM has a hydrophobic signal peptide, suggesting that it is a secreted protein subject to proteolytic processing, and it is predicted to be O-glycosylated. SBEM contains 3 tandem copies of a neutral octapeptide core repeat, and its N- and C-terminal regions are charged and fairly polar. These features are similar to many sialomucins, although the protein lacks a transmembrane domain and is shorter than most other known epithelial mucins. RNA hybridization analysis showed SBEM expression in only adult mammary and salivary glands.