Muc1

The mucin-1 alpha subunit has cell adhesion properties, and the protein can act both adhesive and anti-adhesive. Provides a protective layer of epithelial cells against bacteria and damaging enzymes.

The beta subunit plays a role in cell signaling, which is mediated by protein phosphorylation and protein-protein interactions. Mucin-1 modulates signal transmission through ERK , SRC and NF-κB . In activated T cells, it influences the Ras / MAPK signaling pathway . Enhances tumor growth. ^[one]

Mucin-1 is a large protein of 1232 amino acids, which includes 42 repeating sequences of 20 amino acids. Moreover, the number of repeats can vary, which is a consequence of the high polymorphism of the MUC1 gene. The region between amino acids 1097–1098 is autolizing. As a result of hydrolysis of this bond, two subunits are formed, which, after proteolysis, form a non-covalent heterodimer with each other.

The extracellular alpha subunit of mucin-1 (fragment 24–1097) contains adhesive repeats, due to which it binds to ICAM-1 and is involved in cell migration and metastasis of tumor cells. The main isoform 1 directly binds the SH2 domain of the GRB2 protein and forms the MUC1 / GRB2 / SOS1 complex , which is responsible for the transmission of Ras- mediated signal.

The mucin-1 cytoplasmic beta subunit (fragment 1098–1255) contains a large number of regulatory protein binding sites and determines the participation of mucin-1 in several signaling pathways. The beta subunit binds SRC, CTNNB1 and proteins of the ERB group.

Cells with more than 80% carcinomas are characterized by high expression of mucin-1, a change in glycosylation profile, and loss of polarization. A high level of glycosylation of this protein and a high level of its expression leads to the fact that it forms a layer on the surface of cancer cells that interferes with the penetration of, as a rule, hydrophobic, chemotherapeutic drugs. On the other hand, the mucin layer delays numerous growth factors from the environment surrounding the cell, which leads to their concentration on the cell surface and accelerate the growth of cancer cells. ^[2]

Considered as a possible target for anticancer therapy. ^[3]

• Mucins
• Differentiation cluster

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