Members of the trefoil family are characterized by having at least one copy of the trefoil motif, a 40-amino acid domain that contains three conserved disulfides. They are stable secretory proteins expressed in gastrointestinalmucosa. Their functions are not defined, but they may protect the mucosa from insults, stabilize the mucus layer, and affect healing of the epithelium. This gene, which is expressed in the gastric mucosa, has also been studied because of its expression in human tumors. This gene and two other related trefoil family member genes are found in a cluster on chromosome 21.[6]
All three human trefoil factors are lectins that interact specifically with the disaccharideGlcNAc-α-1,4-Gal.[8] This disaccharide is an unusual glycotope that is only known to exist on the large, heavily glycosylated, mucins in the mucosa. By cross-linking mucins through the bivalent binding of this glycotope, the trefoil factors are then able to reversibly modulate the thickness and viscosity of the mucus.[8]
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Seib T, Blin N, Hilgert K, Seifert M, Theisinger B, Engel M, Dooley S, Zang KD, Welter C (1997). "The three human trefoil genes TFF1, TFF2, and TFF3 are located within a region of 55 kb on chromosome 21q22.3". Genomics. 40 (1): 200–2. doi:10.1006/geno.1996.4511. PMID9070946.
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