Mucin-1 SEA domain (MUC1 SEA domain)

The **Mucin-1 SEA domain** is a highly conserved, extracellular protein domain of approximately 110–120 amino acids found in the membrane-proximal region of the transmembrane mucin-1 (MUC1) glycoprotein and related mucins[1][2][8]. During biosynthesis, the SEA domain undergoes a unique, autocatalytic cleavage (autoproteolysis) between a conserved glycine and serine in the GSVVV motif, generating two subunits (N-terminal and C-terminal) that remain noncovalently associated through strong β-sheet interactions[1][3][4]. This cleavage is essential for MUC1 surface expression and may act as a "molecular break point" that protects epithelial cells from excessive mechanical stress at mucosal surfaces, thus functioning as a mechanical force sensor[1][3][6]. Many SEA domain–containing mucins, including MUC1, are overexpressed and abnormally glycosylated in epithelial cancers, making MUC1 an important diagnostic and therapeutic target, although the SEA domain itself is not generally targeted by existing drugs[4][7]. The structure and autoproteolytic mechanism of the SEA domain have been elucidated by NMR and X-ray crystallography[2][3].

Other names

SEA domain of mucin-1SEA module of MUC1MUC1 SEAsperm protein–enterokinase–agarin domain of MUC1

Null (drugs targeting MUC1 typically work through antibody recognition of MUC1 extracellular epitopes, not by directly interacting with the SEA domain)[7]