SQV-7, a protein involved in Caenorhabditis elegans epithelial invagination and early embryogenesis, transports UDP-glucuronic acid, UDP-N-acetylgalactosamine, and UDP-galactose

Patricia Berninsone, Ho-Yon Hwang, Irina Zemtseva, H. Robert Horvitz, Carlos B. Hirschberg

Research output: Contribution to journalArticle


Caenorhabditis elegans sqv mutants are defective in vulval epithelial invagination and have a severe reduction in hermaphrodite fertility. The gene sqv-7 encodes a multitransmembrane hydrophobic protein resembling nucleotide sugar transporters of the Golgi membrane. A Golgi vesicle enriched fraction of Saccharomyces cerevisiae expressing SQV-7 transported UDP-glucuronic acid, UDP-N-acetylgalactosamine, and UDP-galactose (Gal) in a temperature-dependent and saturable manner. These nucleotide sugars are competitive, alternate, noncooperative substrates. The two mutant sqv-7 missense alleles resulted in a severe reduction of these three transport activities. SQV-7 did not transport CMP-sialic acid, GDP-fucose, UDP-N-acetylglucosamine, UDP-glucose, or GDP-mannose. SQV-7 is able to transport UDP-Gal in vivo, as shown by its ability to complement the phenotype of Madin-Darby canine kidney ricin resistant cells, a mammalian cell line deficient in UDP-Gal transport into the Golgi. These results demonstrate that unlike most nucleotide sugar transporters, SQV-7 can transport multiple distinct nucleotide sugars. We propose that SQV-7 translocates multiple nucleotide sugars into the Golgi lumen for the biosynthesis of glycoconjugates that play a pivotal role in development.

Original languageEnglish (US)
Pages (from-to)3738-3743
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number7
Publication statusPublished - Mar 27 2001
Externally publishedYes


ASJC Scopus subject areas

  • Genetics
  • General

Cite this