title: Endoplasmic reticulum: Where nucleotide sugar transport meets cytokinin control mechanisms.
abstract: The endoplasmic reticulum (ER) is a multifunctional eukaryotic organelle where the vast majority of secretory proteins are folded and assembled to achieve their correct tertiary structures. The lumen of the ER and Golgi apparatus also provides an environment for numerous glycosylation reactions essential for modifications of proteins and lipids, and for cell wall biosynthesis. These glycosylation reactions require a constant supply of cytosolically synthesized substrate precursors, nucleotide sugars, which are transported by a group of dedicated nucleotide sugar transporters (NST). Recently, we have reported on the identification of a novel ER-localized NST protein, ROCK1, which mediates the transport of UDP-linked acetylated hexosamines across the ER membrane in Arabidopsis. Interestingly, it has been demonstrated that the activity of ROCK1 is important for the regulation of cytokinin-degrading enzymes, cytokinin oxidases/dehydrogenases (CKX), in the ER and, thus, for cytokinin responses. In this addendum we will address the biochemical and cellular activity of the ROCK1 transporter and its phylogenetic relation to other NST proteins.
authors.affiliation: a Institute of Biology/Applied Genetics; Dahlem Center of Plant Sciences (DCPS); Freie Universität Berlin ; Berlin , Germany.
authors.forename: Michael C E
authors.initials: MC
authors.lastname: Niemann
authors.affiliation: a Institute of Biology/Applied Genetics; Dahlem Center of Plant Sciences (DCPS); Freie Universität Berlin ; Berlin , Germany.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Werner
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006595:Hexosamines / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D033704:Nucleotide Transport Proteins / Q000235:genetics / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism*; D010802:Phylogeny
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D003583:Cytokinins; D006595:Hexosamines; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D033704:Nucleotide Transport Proteins; D009711:Nucleotides; C000597092:ROCK1 protein, Arabidopsis
keywords: CKX; NST; ROCK1; cytokinin; endoplasmic reticulum; meristem; nucleotide sugar; quality control