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Glycosyltransferase Families (glycosyltransferase + family)
Selected AbstractsSaccharomyces cerevisiae Ybr004c and its human homologue are required for addition of the second mannose during glycosylphosphatidylinositol precursor assemblyFEBS JOURNAL, Issue 5 2005Anne-Lise Fabre Addition of the second mannose is the only obvious step in glycosylphosphatidylinositol (GPI) precursor assembly for which a responsible gene has not been discovered. A bioinformatics-based strategy identified the essential Saccharomyces cerevisiae Ybr004c protein as a candidate for the second GPI ,-mannosyltransferase (GPI-MT-II). S. cerevisiae cells depleted of Ybr004cp have weakened cell walls and abnormal morphology, are unable to incorporate [3H]inositol into proteins, and accumulate a GPI intermediate having a single mannose that is likely modified with ethanolamine phosphate. These data indicate that Ybr004cp-depleted yeast cells are defective in second mannose addition to GPIs, and suggest that Ybr004cp is GPI-MT-II or an essential subunit of that enzyme. Ybr004cp homologues are encoded in all sequenced eukaryotic genomes, and are predicted to have 8 transmembrane domains, but show no obvious resemblance to members of established glycosyltransferase families. The human Ybr004cp homologue can substitute for its S. cerevisiae counterpart in vivo. [source] Three monophyletic superfamilies account for the majority of the known glycosyltransferasesPROTEIN SCIENCE, Issue 7 2003Jing Liu Abstract Sixty-five families of glycosyltransferases (EC 2.4.x.y) have been recognized on the basis of high-sequence similarity to a founding member with experimentally demonstrated enzymatic activity. Although distant sequence relationships between some of these families have been reported, the natural history of glycosyltransferases is poorly understood. We used iterative searches of sequence databases, motif extraction, structural comparison, and analysis of completely sequenced genomes to track the origins of modern-type glycosyltransferases. We show that >75% of recognized glycosyltransferase families belong to one of only three monophyletic superfamilies of proteins, namely, (1) a recently described GPGTF/GT-B superfamily; (2) a nucleoside-diphosphosugar transferase (GT-A) superfamily, which is characterized by a DxD sequence signature and also includes nucleotidyltransferases; and (3) a GT-C superfamily of integral membrane glycosyltransferases with a modified DxD signature in the first extracellular loop. Several developmental regulators in Metazoans, including Fringe and Egghead homologs, belong to the second superfamily. Interestingly, Tout-velu/Exostosin family of developmental proteins found in all multicellular eukaryotes, contains separate domains belonging to the first and the second superfamilies, explaining multiple glycosyltransferase activities in one protein. [source] A novel member of the glycosyltransferase family, ,3Gn-T2, highly downregulated in invasive human bladder transitional cell carcinomasMOLECULAR CARCINOGENESIS, Issue 2 2001Irina Gromova Abstract Differential display reverse transcription (DDRT),polymerase chain reaction (PCR) was used to compare the transcriptomes of invasive and noninvasive fresh human bladder transitional cell carcinomas. A differentially expressed novel gene sharing structural similarity with the human ,3-galactosyltransferase family, ,-1,3- N -acetylglucosaminyltransferase-T2 (,3Gn-T2), was identified. The full-length ,3Gn-T2 cDNA, containing a complete open reading frame of 1193 bp, was cloned and sequenced. ,3Gn-T2 exhibited 29,41% homology to the multigene ,3-galactosyltransferase family. Expression of the full-length ,3Gn-T2 cDNA in an in vitro coupled transcription/translation assay yielded a primary translation product with an apparent Mr of 46 kDa, which is in agreement with the predicted 397-amino-acid protein encoded by ,3Gn-T2. Multiple peptide alignment showed several sequence motifs corresponding to putative catalytic domains that are conserved throughout all members of the ,3-galactosyltransferase family, namely, a type II transmembrane domain, a conserved DxD motif, an N -glycosylation site, and five conserved cysteins. By RT-PCR strong downregulation of ,3Gn-T2 expression was noted in invasive human bladder transitional cell carcinomas (16 fresh biopsy samples: grade III, T2,T4) compared with their noninvasive counterparts (15 fresh biopsies: grade II, Ta), suggesting that ,3Gn-T2 may be involved in cancer progression. © 2001 Wiley-Liss, Inc. [source] Rice cellulose synthase-like D4 is essential for normal cell-wall biosynthesis and plant growthTHE PLANT JOURNAL, Issue 6 2009Ming Li Summary Cellulose synthase-like (CSL) proteins of glycosyltransferase family 2 (GT2) are believed to be involved in the biosynthesis of cell-wall polymers. The CSL D sub-family (CSLD) is common to all plants, but the functions of CSLDs remain to be elucidated. We report here an in-depth characterization of a narrow leaf and dwarf1 (nd1) rice mutant that shows significant reduction in plant growth due to retarded cell division. Map-based cloning revealed that ND1 encodes OsCSLD4, one of five members of the CSLD sub-family in rice. OsCSLD4 is mainly expressed in tissues undergoing rapid growth. Expression of OsCSLD4 fluorescently tagged at the C- or N-terminus in rice protoplast cells or Nicotiana benthamiana leaves showed that the protein is located in the endoplasmic reticulum or Golgi vesicles. Golgi localization was verified using phenotype-rescued transgenic plants expressing OsCSLD4,GUS under the control of its own promoter. Two phenotype-altered tissues, culms and root tips, were used to investigate the specific wall defects. Immunological studies and monosaccharide compositional and glycosyl linkage analyses explored several wall compositional effects caused by disruption of OsCSLD4, including alterations in the structure of arabinoxylan and the content of cellulose and homogalacturonan, which are distinct in the monocot grass species Oryza sativa (rice). The inconsistent alterations in the two tissues and the observable structural defects in primary walls indicate that OsCSLD4 plays important roles in cell-wall formation and plant growth. [source] | ||||||||||