FIG. 2. Common topology of cloned terminal glycosyltransferases. Deduced amino acid sequences of the terminal glycosyltransferases cloned to date predict that these enzymes have a characteristic topology in the Golgi apparatus consisting of a short NH2-terminal cytoplasmic tail, a signal-anchor domain which spans the membrane, an extended stem region, and a large COOH-terminal catalytic domain oriented within the lumen of the Golgi cisternae. at the 5'end have also been reported for the murine GlcNAc/31, 4-GT which code for enzymes that differ only by 13 amino acids at the NH, terminus (10).