Mucin-4

Mucin-4 (MUC4) is a large transmembrane mucin that is part of the mucin family. It is encoded by the MUC4 gene in humans. MUC4 is known for its role in the protection and lubrication of epithelial surfaces, and it is also involved in various pathological conditions, including cancer.

Structure

MUC4 is a high molecular weight glycoprotein that is characterized by its extensive O-glycosylation. The protein is composed of two subunits, MUC4α and MUC4β, which are held together by non-covalent interactions. The MUC4α subunit contains a large extracellular domain with numerous tandem repeat regions, which are responsible for the protein's heavy glycosylation. The MUC4β subunit, on the other hand, contains a transmembrane domain and a short cytoplasmic tail.

Function

MUC4 plays a crucial role in the protection and lubrication of various epithelial surfaces, including the respiratory tract, gastrointestinal tract, and reproductive system. It forms a physical barrier that prevents pathogens from adhering to the epithelial cells. MUC4 also has a role in cell signaling, as it can interact with other proteins to regulate cell growth and differentiation.

Clinical significance

Alterations in MUC4 expression have been associated with several types of cancer, including pancreatic cancer, breast cancer, and lung cancer. In these cancers, MUC4 is often overexpressed, and its expression level is correlated with tumor progression and poor prognosis. MUC4 can promote tumor growth and metastasis by interacting with other proteins, such as the epidermal growth factor receptor (EGFR).

See also

• Mucin
• Mucin-1
• Mucin-2
• Mucin-3

References

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