Molecular cloning of a novel α2,3-sialyltransferase (ST3Gal VI) that sialylates type II lactosamine structures on glycoproteins and glycolipids

Tetsuya Okajima, Satoshi Fukumoto, Hiroshi Miyazaki, Hideharu Ishida, Makoto Kiso, Keiko Furukawa, Takeshi Urano, Koichi Furukawa

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133 Citations (Scopus)

Abstract

A novel member of the human CMP-NeuAc:β-galactoside α2,3- sialyltransferase (ST) subfamily, designated ST3Gal VI, was identified based on BLAST analysis of expressed sequence tags, and a cDNA clone was isolated from a human melanoma line library. The sequence of ST3Gal VI encoded a type II membrane protein with 2 amino acids of cytoplasmic domain, 32 amino acids of transmembrane region, and a large catalytic domain with 297 amino acids; and showed homology to previously cloned ST3Gal III, ST3Gal IV, and ST3Gal V at 34, 38, and 33%, respectively. Extracts from L cells transfected with ST3Gal VI cDNA in a expression vector and a fusion protein with protein A showed an enzyme activity of α2,3-sialyltransferase toward Galβ1,4GlcNAc structure on glycoproteins and glycolipids. In contrast to ST3Gal III and ST3Gal IV, this enzyme exhibited restricted substrate specificity, i.e. it utilized Galβ1, 4GlcNAc on glycoproteins, and neolactotetraosylceramide and neolactohexaosylceramide, but not lactotetraosylceramide, lactosylceramide, or asialo-GM1. Consequently, these data indicated that this enzyme is involved in the synthesis of sialyl-paragloboside, a precursor of sialyl- Lewis X determinant.

Original languageEnglish
Pages (from-to)11479-11486
Number of pages8
JournalJournal of Biological Chemistry
Volume274
Issue number17
DOIs
Publication statusPublished - Apr 23 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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