Functions as an intestinal M-cells transcytotic receptor specific of type-I-piliated bacteria that participate in the mucosal immune response toward these bacteria. At the apical membrane of M-cells binds fimH, a protein of the bacteria type I pilus tip. Internalizes bound bacteria, like E.coli and S.typhimurium, from the lumen of the intestine and delivers them, through M-cells, to the underlying organized lymphoid follicles where they are captured by antigen-presenting dendritic cells to ellicit a mucosal immune response.

> 85% as determined by SDS-PAGE.