Preliminary characterization of a Chinese hamster ovary cell glycosylation mutant isolated by screening for low intracellular lysosomal enzyme activity |
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| Authors: | Clara W Hall April R Robbins Sharon S Krag |
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| Institution: | (1) Genetics and Biochemistry Branch, NIADDK, National Institutes of Health, 20892 Bethesda, MD, USA;(2) Department of Biochemistry, The Johns Hopkins University, School of Hygiene and Public Health, 21205 Baltimore, MD, USA;(3) Department of Biochemistry The Johns Hopkins University, School of Hygiene and Public Health, 21205 Baltimore, MD, USA |
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| Abstract: | A novel screening procedure was developed for isolating Chinese hamster ovary cell mutants altered in the early steps of the biosynthesis of asparagine-linked glycoproteins. This procedure identifies cells with low intracellular levels of two lysosomal hydrolases, beta-glucuronidase and alpha-iduronidase. One mutant cell line isolated in this way, CHB 11-1-3, has low intracellular levels of seven lysosomal enzymes as compared to wild-type cells. Although CHB 11-1-3 synthesizes mannosylphosphoryldolichol and Man]5NAcG1cNH2]2-P-P-lipid, it fails to utilize these lipid intermediates to make normal amounts of Glc]3Man]9NAcG1cNH2]2P-P-lipid. As a consequence of this glycosylation defect, this mutant transfers oligosaccharides of a different structure than wild type to the lysosomal enzyme beta-hexosaminidase. In addition, it underglycosylates its proteins. |
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| Keywords: | lysosomal enzymes glycosylation dolichol intermediates asparagine-linked glycoproteins |
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