Characterization of rat N-acetylglucosaminyltransferase I expressed in Escherichia coli

The catalytic domain (sGnT-I) of rat liver N-acetylglucosaminyl-transferase I (GnT-I) was expressed in Escherichia coli. Lysates from pETsGnT-I transformants contained a prominent protein species of 46 kDa with which a significant GnT-I activity was associated. To purify the relevant enzyme, we constructed cDNAs encoding sGnT-ICH and sGnT-INH, which had six additional histidine residues as an affinity tag at the C-terminal and the N-terminal of sGnT-I, respectively, and introduced them into E. coli cells for expression. sGnT-INH was purified and its enzymatic properties were examined.