Complementing mutant alleles define three loci involved in mannosylation of Man5-GlcNAc2-P-P-dolichol in Chinese hamster ovary cells

Pamela J. Beck, Mary Jane Gething, Joseph Sambrook, Mark A. Lehrman

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Dolichol-linked oligosaccharides consisting of two N-acetylglucosamine, nine mannose, and three glucose residues (Glc3Man9GlcNAc2) are transferred to proteins that contain the consensus sequence Asn-X-Ser/Thr. This transfer occurs upon protein import into the lumen of the endoplasmic reticulum. An intermediate in the biosynthesis of the Glc3Man9GlcNAc2 lipid-linked oligosaccharide contains two GlcNAc and five mannose residues. This intermediate serves as a substrate for further mannosylation and glucosylation before transfer to protein. The addition of the sixth mannose residue to this intermediate requires the enzyme mannosyltransferase VI and the mannose donor, mannose-P-dolichol. Several different CHO cell line mutants that fail to efficiently catalyze this transfer have been described. In this report, we examine seven independent mutant cell lines with various biochemical phenotypes and demonstrate that all can be assigned to one of three genetic complementation groups. One mutation affects mannose-P-dolichol biosynthesis (Lec15), three affect dolichol phosphate biosynthesis (Lec9), and three appear to affect the functional orientation of enzyme substrates (PIR).

Original languageEnglish (US)
Pages (from-to)539-548
Number of pages10
JournalSomatic Cell and Molecular Genetics
Volume16
Issue number6
DOIs
StatePublished - Nov 1 1990

ASJC Scopus subject areas

  • Genetics
  • Cell Biology

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