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Strasser, R; Schoberer, J; Jin, C; Glössl, J; Mach, L; Steinkellner, H; .
(2006): Molecular cloning and characterization of Arabidopsis thaliana Golgi alpha-mannosidase II, a key enzyme in the formation of complex N-glycans in plants.
Plant J. 2006; 45(5):789-803 FullText FullText_BOKU

Abstract:
N-glycosylation is one of the major post-translational modifications of proteins in eukaryotes; however, the processing reactions of oligomannosidic N-glycan precursors leading to hybrid-type and finally complex-type N-glycans are not fully understood in plants. To investigate the role of Golgi alpha-mannosidase II (GMII) in the formation of complex N-glycans in plants, we identified a putative GMII from Arabidopsis thaliana (AtGMII; EC 3.2.1.114) and characterized the enzyme at a molecular level. The putative AtGMII cDNA was cloned, and its deduced amino acid sequence revealed a typical type II membrane protein of 1173 amino acids. A soluble recombinant form of the enzyme produced in insect cells was capable of processing different physiologically relevant hybrid N-glycans. Furthermore, a detailed N-glycan analysis of two AtGMII knockout mutants revealed the predominant presence of unprocessed hybrid N-glycans. These results provide evidence that AtGMII plays a central role in the formation of complex N-glycans in plants. Furthermore, conclusive evidence was obtained that alternative routes in the conversion of hybrid N-glycans to complex N-glycans exist in plants. Transient expression of N-terminal AtGMII fragments fused to a GFP reporter molecule demonstrated that the transmembrane domain and 10 amino acids from the cytoplasmic tail are sufficient to retain a reporter molecule in the Golgi apparatus and that lumenal sequences are not involved in the retention mechanism. A GFP fusion construct containing only the transmembrane domain was predominantly retained in the ER, a result that indicates the presence of a motif promoting ER export within the last 10 amino acids of the cytoplasmic tail of AtGMII.
Authors BOKU Wien:
Glößl Josef
Mach Lukas
Schoberer Jennifer
Steinkellner Herta
Strasser Richard
BOKU Gendermonitor:

Find related publications in this database (using NML MeSH Indexing)
Amino Acid Sequence;Animals;Arabidopsis/enzymology*;Arabidopsis/genetics;Glycopeptides;Golgi Apparatus/metabolism;Mannosidases/metabolism*;Molecular Sequence Data;Mutagenesis, Insertional;Oligosaccharides, Branched-Chain/metabolism*;Sequence Analysis, DNA;Spodoptera/genetics;Substrate Specificity;Transfection;

Find related publications in this database (Keywords)
Golgi mannosidase II
glycosyl hydrolase
Arabidopsis thaliana
N-glycosylation
Golgi targeting


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