About MUC21
This gene encodes a large membrane-bound glycoprotein which is a member of the mucin family. Mucins are O-glycosylated proteins that play an essential role in forming protective mucous barriers on epithelial surfaces. These proteins also play a role in intracellular signaling. The encoded protein contains an N-terminal signal sequence, an extracellular mucin domain, a stem domain, a transmembrane domain, and a C-terminal cytoplasmic tail domain. The mucin domain contains O-glycosylation sites and is polymorphic with isoforms containing a variable number of nonidentical proline-, threonine-, and serine-rich tandem repeats of 15 amino acids each. The aberrent expression of this gene is associated with lung adenocarcinoma. [provided by RefSeq, May 2017]