Mucin 21 (MUC21)

Mucin 21, cell surface associated, also known as MUC21, is a protein encoded by the MUC21 gene. Mucin proteins penetrate the membranes of epithelial cells, on the inner surface of the intestine and other organs. Mucin protects the body from infection by binding to pathogens. Overexpression of the mucin protein is often associated with colon and many other cancers. Mucins are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by many epithelial tissues in vertebrates. They bind to pathogens as part of the immune system. Although some mucins are membrane-bound due to the presence of a hydrophobic membrane-spanning domain that favors retention in the plasma membrane, most mucins are secreted onto mucosal surfaces or secreted to become a component of saliva.