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

P Berninsone, HY Hwang, I Zemtseva… - Proceedings of the …, 2001 - National Acad Sciences
P Berninsone, HY Hwang, I Zemtseva, HR Horvitz, CB Hirschberg
Proceedings of the National Academy of Sciences, 2001National Acad Sciences
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 …
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.
National Acad Sciences