A mouse
cDNA clone previously isolated from an F9
teratocarcinoma cell library and shown to confer
N-acetylglucosaminyltransferase I (
GlcNAc-TI) activity on Lec1 Chinese hamster ovary (CHO) cell transfectants [Kumar, R., Yang,J., Larsen,R.D. and Stanley,P. (1990) Proc. Natl. Acad Sci. USA, 87, 9948-9952] has been sequenced. The
nucleotide and deduced amino acid sequences are highly homologous to previously described human and rabbit
GlcNAc-TI cDNAs. A 1250 bp portion of the mouse
cDNA encoding all but the first 34
amino acids of the deduced
protein sequence was inducibly expressed in Escherichia coli and gave rise to a prominent fusion
protein of mol. wt approximately 45 kDa whose presence correlated with high levels of
GlcNAc-TI activity in cell lysates. Probes generated from the
cDNA were used to show that the
GlcNAc-TI gene is present in a single copy in mammals and that a homologous gene was not detectable (under low-stringency hybridization conditions) in
DNA from yeast, sea urchin, Drosophila or Chaenorhaditis elegans. Genomic
DNA clones that hybridized to probes generated from the
GlcNAc-TI cDNA were isolated from a mouse liver library. Restriction analyses, Southern hybridization and DNA sequence analyses of subcloned genomic
DNA fragments and a polymerase chain reaction (PCR) product provided evidence that the coding and
3' untranslated regions of the
cDNA reside in a single exon. However, the mouse
GlcNAc-TI gene (Mgat-1) includes at least one additional exon 5' of the coding region. Southern analyses of
DNA from mouse-human somatic cell hybrids and in situ hybridization were used to locate the human
GlcNAc-TI gene (MGAT-1) between positions q31.2 and q31.3 on chromosome 5, a region of chromosome 5 that is syntenic with a region of mouse chromosome 11. Northern analyses of adult mouse tissues revealed two
GlcNAc-TI gene transcripts that are differentially expressed in different tissues.