Članovi porodice Trefoil odlikuju se po tome što imaju najmanje jednu kopiju trefoilski motiv, domena od 40 aminokiselina koji sadrži tri konzervirana disulfida. To su stabilni sekretorni proteini eksprimirani u gastrointestinalnosluzokoži. Njihove funkcije nisu definirane, ali mogu zaštititi sluznicu od ozljeda, stabilizirati sloj sluzi i uticati na zacjeljivanje epitela. Ovaj gen, koji je eksprimiran u sluznici želuca, također je proučavan zbog njegove ekspresije u ljudskim tumorima. Sa dva druga srodna gena člana porodice trefiola nalaze se u klasteru na hromosomu 21.[6]
Vezivanje glikana
Sva tri ljudska trefoilska faktora su lektini koji su u specifičnoj interakciji sa disaharidom GlcNAc-α-1,4-Gal.[8] Ovaj disaharid je neobičan glikotop za koji se zna da postoji samo na velikim, jako glikozilovanim, mucinima u sluznici. Unakrsnim povezivanjem mucina putem dvovalentno vezivanje ovog glikotopa, trefiolni faktori su tada u stanju da reverzibilno moduliraju debljinu i viskoznost sluzi.[8]
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