Y. Ihara et al., CDNA CLONING, EXPRESSION, AND CHROMOSOMAL LOCALIZATION OF HUMAN N-ACETYLGLUCOSAMINYLTRANSFERASE-III (GNT-III), Journal of Biochemistry, 113(6), 1993, pp. 692-698
UDP-N-acetylglucosamine: beta-D-mannoside beta1,4 N-acetylglucosaminyl
transferase III (GnT-III) [EC 2.4.1.144] catalyzes the addition of N-a
cetylglucosamine in beta1-4 linkage to the beta-linked mannose of the
trimannosyl core of N-linked sugar chains to produce a bisecting GlcNA
c residue. We have isolated six independent cDNA clones of human GnT-I
II from a fetal liver cDNA library. The cDNA sequence has an open read
ing frame that predicts a protein of 531 amino acids. The homology to
rat GnT-III is 86% at the nucleotide level and is 91% at the amino aci
d level. The amino-terminal transmembrane domain and the catalytic dom
ain are well conserved in the two species. Human GnT-III has a deletio
n of four amino acids in the ''neck'' region and several differences i
n the COOH-terminal region compared with the rat sequence. Using one o
f the human cDNA clones as the probe, two overlapping genomic clones h
ave been isolated from a human cosmid library. The GnT-III gene has be
en mapped to chromosome 22q.13.1 using fluorescence in situ hybridizat
ion.