Functional characterization of Gms1p/UDP-galactose transporter in Schizosaccharomyces pombe

Naotaka Tanaka, Kaoru Takegawa

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Galactosylation of glycoproteins in the fission yeast Schizosaccharomyces pombe requires the transport of UDP-galactose as substrate for the galactosyltransferase into the lumen of the Golgi apparatus, which is achieved by the UDP-galactose transporter. We isolated a mutant (gms1) that is deficient in galactosylation of cell surface glycoproteins in Sz. pombe, and found that the gms1+ gene encodes a UDP-galactose transporter. In the prediction of secondary structure of the Gms1 protein, an eight-membrane-spanning structure was obtained. Fluorescent microscopy revealed the functional Gms1-GFP fusion protein to be stably localized at the Golgi membrane. Sequencing analysis of the coding region of Gms1p derived from galactosylation-defective mutants identified a single amino acid mutation (A102T or A258E) located within the putative transmembrane region, helix 2 or helix 7, respectively. The mutagenized Gms1(A102T or A258E)p exhibited loss of UDP-galactose transport activity but no change in the localization to the Golgi membrane. The C-terminal truncated Gms1p mutants demonstrated that the C-terminal hydrophilic region was dispensable for targeting and function as UDP-galactose transporter at the Golgi membrane. We suggest that the putative eighth (the most C-terminus-proximal) transmembrane helix of Gms1p is critical to targeting from ER to the Golgi membrane.

Original languageEnglish
Pages (from-to)745-757
Number of pages13
JournalYeast
Volume18
Issue number8
DOIs
Publication statusPublished - Jun 15 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Genetics

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