Glycosyltransferase that initiates the elongation of O-linked fucose residues attached to EGF-like repeats in the extracellular domain of Notch molecules (By similarity). Involved in forelimb development and in adult forelimb regeneration. 3-O-(alpha-L-fucosyl)-L-threonyl-[EGF-like domain protein] + UDP-N-acetyl-alpha-D-glucosamine = 3-O-(N-acetyl-beta-D-glucosaminyl-(1->3)-alpha-L-fucosyl)-L-threonyl-[EGF-like domain protein] + H(+) + UDP 3-O-(alpha-L-fucosyl)-L-seryl-[EGF-like domain protein] + UDP-N-acetyl-alpha-D-glucosamine = 3-O-(N-acetyl-beta-D-glucosaminyl-(1->3)-alpha-L-fucosyl)-L-seryl-[EGF-like domain protein] + H(+) + UDP Detected in the mesanchymal region of the developing limb. Expressed in mesoderm but not in ectoderm with no evident boundary of expression. First detected in the presumptive limb field. As the limb develops from a limb bud into a cone, a stron homogeneous signal is evident. Strong expression persists as the cone flattens into a palette and digits begin to appear and is down-regulated as limb development advances. At the three digit stage there is a faint mesenchymal expression which disappears at the appearance of the fourth digit. Belongs to the glycosyltransferase 31 family.