The function of FUT1 (fucosyltransferase 1 (H blood group), Ensembl gene identifier ENSG00000174951) is as follows. Catalyzes the transfer of L-fucose, from a guanosine diphosphate-beta-L-fucose, to the terminal galactose residue of glycoconjugates through an alpha(1,2) linkage leading to H antigen synthesis that is an intermediate substrate in the synthesis of ABO blood group antigens (PubMed:2118655). H antigen is essential for maturation of the glomerular layer of the main olfactory bulb, in cell migration and early cell-cell contacts during tumor associated angiogenesis (PubMed:18205178). Preferentially fucosylates soluble lactose and to a lesser extent fucosylates glycolipids gangliosides GA1 and GM1a (By similarity). {ECO:0000250|UniProtKB:O09160, ECO:0000269|PubMed:18205178, ECO:0000269|PubMed:2118655}.