Preferentially catalyzes the addition of fucose in alpha 1-3 linkage to the first GlcNAc residue (with or without alpha 1,6-linked fucose), next to the peptide chains in N-glycans (PubMed:15364955, PubMed:9675224, PubMed:17369288, PubMed:21515584). Unlike in mammals, does not require the prior action of N-acetylglucosaminyltransferase I to generate complex N-glycans (PubMed:15364955). GDP-beta-L-fucose + N(4)-{beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc}-L-asparaginyl-[protein] = GDP + H(+) + N(4)-{beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-[(1->4)-alpha-L-Fuc]-beta-D-GlcNAc}-L-asparaginyl-[protein] Can also use Co(2+) or Ca(2+) in vitro. Inhibited by Cu(2+) or Zn(2+) and to a lesser extent Ni(2+) ions. Optimum temperature is 23 degrees Celsius. No detectable activity at 37 degrees Celsius. Protein modification; protein glycosylation. Expressed in the pharyngeal-intestinal (PI) and anal valves. Expressed in ASG neurons and in one or two neurons in the retrovesicular ganglion and two neurons posterior to the PI valve and PHA and PHB neurons in the tail. Expressed throughout development and in adult. The C-terminus (424-433) is important for catalytic activity or for enzyme stability. The N-terminus (1-78) appears to be dispensable for enzymatic activity. N-glycosylated (PubMed:17369288, PubMed:21515584). Glycosylation is important for enzymatic activity (PubMed:21515584). Belongs to the glycosyltransferase 10 family.