A novel β(1,6)-N-acetylglucosaminyltransferase V (GnT-VB)

Mika Kaneko, Gerardo Alvarez-Manilla, Maria Kamar, Intaek Lee, Jin Kyu Lee, Karolyn Troupe, Wei Jie Zhang, Motoki Osawa, Michael Pierce

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

UDP-N-acetylglucosamine:α(1,6)-D-mannoside β(1,6)-N- acetylglucosaminyltransferase (GnT-V, Mgat5) functions in the biosynthesis of N-linked glycans and is transcriptionally upregulated by oncogene signaling. We report here the cloning and characterization of a human cDNA encoding a distinct enzyme with related substrate specificity, termed GnT-VB, which is predicted to have 53% similarity to the original amino acid sequence of GnT-V(A). Transient expression of GnT-VB cDNA in COS7 cells yielded significant increases of activity toward GnT-VA acceptors, including synthetic saccharides and N-linked glycopeptides, with some differences in specificity. Unlike GnT-VA, GnT-VB required divalent cation for full activity. EST databases showed expression of a 6 bp (+) splice isoform of GnT-VB; when expressed, this enzyme showed significantly reduced activity. CHO Lec4 cells, which do not express GnT-VA or B activity, lack synthesis of the N-linked β(1,6) branch, and do not bind L-phytohemagglutinin (L-PHA), were transfected with GnT-VB or GnT-VA; both then bound significant amounts of L-PHA, demonstrating that both enzymes synthesized N-linked β(1,6) branched glycans in vivo. Real-time polymerase chain reaction results showed that GnT-VB mRNA was highly expressed in brain and testis, with lesser levels in other tissues, while human GnT-VA showed a more general expression, but with low levels in brain and no expression in skeletal muscle.

Original languageEnglish
Pages (from-to)515-519
Number of pages5
JournalFEBS Letters
Volume554
Issue number3
DOIs
Publication statusPublished - 2003 Nov 20
Externally publishedYes

Keywords

  • Glycosyltransferase
  • L-Phytohemagglutinin
  • N-Linked β(1,6) branch
  • UDP-N-acetylglucosamine:α(1,6)-D-mannoside β(1,6)-N-acetylglucosaminyltransferase

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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