title: Isolation of the ALG5 locus encoding the UDP-glucose:dolichyl-phosphate glucosyltransferase from Saccharomyces cerevisiae.
abstract: UDP-glucose:dolichyl-phosphate glucosyltransferase is a transmembrane-bound enzyme of the endoplasmic reticulum involved in protein N-linked glycosylation. This enzyme catalyzes the transfer of glucose from UDP-glucose to dolichyl phosphate. The structural gene encoding this transferase from Saccharomyces cerevisiae was isolated by complementation of an alg5-1 mutation. DNA sequencing of ALG5 revealed an open-reading frame of 1002 bases encoding a transmembrane protein of molecular mass 38.3 kDa. Overexpression of Alg5p in both yeast and Escherichia coli results in an increase of UDP-glucose:dolichyl-phosphate glucosyltransferase activity, whereas a deletion of the yeast gene leads to a loss of this activity and a concomitant underglycosylation of carboxypeptidase Y. The ALG5 protein has sequence similarity to the GDP-mannose:dolichyl-phosphate mannosyltransferase (Dpm1p) from S. cerevisiae. Topological studies indicate that UDP-glucose:dolichyl-phosphate glucosyltransferase is a transmembrane protein that spans the membrane several times.
authors.affiliation: Mikrobiologisches Institut, ETH Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Heesen
authors.forename: L
authors.initials: L
authors.lastname: Lehle
authors.forename: A
authors.initials: A
authors.lastname: Weissmann
authors.forename: M
authors.initials: M
authors.lastname: Aebi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D004721:Endoplasmic Reticulum / Q000201:enzymology; D004926:Escherichia coli / Q000235:genetics; D005800:Genes, Fungal; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006031:Glycosylation; D007425:Intracellular Membranes / Q000201:enzymology; D008364:Mannosyltransferases / Q000737:chemistry; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014532:Uridine Diphosphate Glucose / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D005964:Glucosyltransferases; D008364:Mannosyltransferases; C033917:UDPglucose dolicholphosphate glucosyltransferase; C022755:dolichyl-phosphate beta-D-mannosyltransferase; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; C022633:serine carboxypeptidase; D014532:Uridine Diphosphate Glucose