Catalyzes the transfer of L-fucose, from a guanosine diphosphate-beta-L-fucose, to the N-acetyl glucosamine (GlcNAc) of a distal alpha2,3 sialylated lactosamine unit of a glycoprotein or a glycolipid-linked sialopolylactosamines chain through an alpha-1,3 glycosidic linkage and participates in the final fucosylation step in the biosynthesis of the sialyl Lewis X (sLe(x)), a carbohydrate involved in cell and matrix adhesion during leukocyte trafficking and fertilization (PubMed:8207002, PubMed:8752218, PubMed:8666674, PubMed:9299472, PubMed:9405391, PubMed:9473504, PubMed:9499379, PubMed:9461592, PubMed:15632313, PubMed:15926890, PubMed:18553500, PubMed:18402946, PubMed:11404359, PubMed:29593094). In vitro, also synthesizes sialyl-dimeric-Lex structures, from VIM-2 structures and both di-fucosylated and trifucosylated structures from mono-fucosylated precursors (PubMed:9499379). However does not catalyze alpha 1-3 fucosylation when an internal alpha 1-3 fucosylation is present in polylactosamine chain and the fucosylation rate of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc (PubMed:9473504, PubMed:9499379). Also catalyzes the transfer of a fucose from GDP-beta-fucose to the 6-sulfated a(2,3)sialylated substrate to produce 6-sulfo sLex mediating significant L-selectin-dependent cell adhesion (PubMed:10200296, PubMed:8752218). Through sialyl-Lewis(x) biosynthesis, can control SELE- and SELP-mediated cell adhesion with leukocytes and allows leukocytes tethering and rolling along the endothelial tissue thereby enabling the leukocytes to accumulate at a site of inflammation (PubMed:10386892, PubMed:29138114, PubMed:8666674, PubMed:9473504, PubMed:9834120). May enhance embryo implantation through sialyl Lewis X (sLeX)-mediated adhesion of embryo cells to endometrium (PubMed:18402946, PubMed:18553500). May affect insulin signaling by up-regulating the phosphorylation and expression of some signaling molecules involved in the insulin-signaling pathway through SLe(x) which is present on the glycans of the INSRR alpha subunit (PubMed:17229154). an N-acetyl-alpha-neuraminyl-(2->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl derivative + GDP-beta-L-fucose = an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc derivative + GDP + H(+) a neolactoside IV(3)-alpha-NeuAc-nLc4Cer + GDP-beta-L-fucose = GDP + H(+) + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-[alpha-L-fucosyl-(1->3)]-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide GDP-beta-L-fucose + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide = GDP + H(+) + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-[alpha-L-fucosyl-(1->3)]-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc derivative + GDP-beta-L-fucose = an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc derivative + GDP + H(+) an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc6S derivative + GDP-beta-L-fucose = an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc6S derivative + GDP + H(+) alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + GDP-beta-L-fucose = alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + GDP + H(+) alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc + GDP-beta-L-fucose = alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc + GDP + H(+) alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc + GDP-beta-L-fucose = alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc + GDP + H(+) Inhibited by NaCl (Probable). Inhibited by GDP in a concentration dependent manner, with an IC(50) value of 93 uM (PubMed:9405391, PubMed:15632313). Also inhibited by GMP and GTP (PubMed:9405391). Inhibited by N-ethylmaleimide (Probable). Activated by poly(ethylene glycol) by enhancing the thermal stability of FUT7 (PubMed:9405391). Activated by Mn2+, Ca2+, and Mg2+ (PubMed:9405391). Both panosialin A and B inhibit activity with IC(50) values of 4.8 and 5.3 ug/ml, respectively (PubMed:10386892). Inhibited by gallic acid (GA) and (-)-epigallocatechin gallate (EGCG) in a time-dependent and irreversible manner with IC(50) values of 60 and 700 nM, respectively (PubMed:15081893). Optimum pH is 7.5. Optimum temperature is 37 degrees Celsius. Protein modification; protein glycosylation. Membrane-bound form in trans cisternae of Golgi. Leukocytic/myeloid lineage cells. By T-cell activation (PubMed:8666674). Up-regulated by LIF (PubMed:19455659). Induced by IL1B (PubMed:29138114). Induced at higher levels by interleukin 12 in activated T cells (PubMed:9858509). Down-regulated by IL4 (PubMed:9858509). N-glycosylated. Belongs to the glycosyltransferase 10 family. Fucosyltransferase 7