The first step in the assembly of the dolichol-linked oligosaccharides required for asparagine-linked glycosylation in eukaryotes is catalyzed by a tunicamycin-sensitive, dolichol phosphate-dependent N-acetylglucosamine-1-phosphate transferase (GPT). A fragment of the gene encoding the enzyme from Chinese hamster ovary (CHO) cells was partially cloned and characterized by a novel strategy. By stepwise selection, CHO cells were made 80-fold resistant to tunicamycin and found to have 10-fold elevated levels of GPT activity. Using a cloned segment of the yeast ALG-7 gene, which encodes the putative GPT from yeast, an amplified gene was identified by Southern blotting of the CHO DNA and a 6.6-kilobase segment of the gene was molecularly cloned. A family of RNA molecules in the 2.0-2.2-kilobase range identified with a probe from this gene was overexpressed in the resistant cells. The cloned DNA revealed a 24-amino acid residue sequence that was 92% conserved with the corresponding yeast sequence.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1988|
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