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Titolo:
The alpha- and beta-subunits are required for expression of catalytic activity in the hetero-dimeric glucosidase II complex from human liver
Autore:
Treml, K; Meimaroglou, D; Hentges, A; Bause, E;
Indirizzi:
Inst Physiol Chem, D-53115 Bonn, Germany Inst Physiol Chem Bonn Germany D-53115 ysiol Chem, D-53115 Bonn, Germany
Titolo Testata:
GLYCOBIOLOGY
fascicolo: 5, volume: 10, anno: 2000,
pagine: 493 - 502
SICI:
0959-6658(200005)10:5<493:TAABAR>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMINO-ACID-SEQUENCE; ASPARAGINE-LINKED OLIGOSACCHARIDES; ENDOPLASMIC-RETICULUM; PIG-LIVER; GLYCOPROTEIN GLUCOSYLTRANSFERASE; DODECYL-SULFATE; QUALITY-CONTROL; HUMAN KIDNEY; UDP-GLC; PROTEINS;
Keywords:
glucosidase II complex; alpha- and beta-subunit; cDNA cloning; alternative splicing; expression of catalytic activity; subcellular localization;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
52
Recensione:
Indirizzi per estratti:
Indirizzo: Bause, E Inst Physiol Chem, Nussallee 11, D-53115 Bonn, Germany Inst Physiol Chem Nussallee 11 Bonn Germany D-53115 onn, Germany
Citazione:
K. Treml et al., "The alpha- and beta-subunits are required for expression of catalytic activity in the hetero-dimeric glucosidase II complex from human liver", GLYCOBIOLOG, 10(5), 2000, pp. 493-502

Abstract

The alpha- and beta-subunits of the hetero-dimeric glucosidase II complex from human liver were cloned and expressed in COS-1 cells. The 4106 bp full-length cDNA for the alpha-subunit contained a 2835 bp ORF encoding a 107 kDa polypeptide. The 2095 bp cDNA for the beta-subunit encodes a similar to 60 kDa protein in a continuous 1605 bp ORF, The a- and beta-subunits each contain two potential Asn-Xaa-Thr/Ser acceptor sites, with only one site in the oc-subunit (Asn97) being glycosglated. Additional lambda-clones were isolated for each subunit containing in-frame insertions/deletions within thecoding region, indicating alternative splicing. Analysis of different human tissues revealed similar to 4.4 kb and similar to 2.4 kb transcripts for alpha- and beta-subunit, respectively, consistent with their full-length cDNA. Coexpression of the alpha- and beta-subunits in COS-1 cells resulted in>4-fold increase of glucosidase II activity, An inactive protein was obtained, however, after transfection with the alpha-subunit alone, showing thatboth subunits are essential for expression of active glucosidase II, The observation that the enzyme, previously purified from pig liver and lacking the beta-subunit, was catalytically active indicates that the beta-subunit is involved in alpha-subunit maturation rather than being required for enzymatic activity once the alpha-subunit has acquired its mature form. The alpha-subunit is expressed in COS-1 cells as an ER-located protein, whether inactive or part of a catalytically active complex, This suggests that ER-localization of the alpha-subunit, when associated with the dimeric enzyme complex, is mediated by the C-terminal HDEL-signal in the beta-subunit, whereas the apparently incompletely folded form of the inactive alpha-subunit could be retained in the ER by the putative "glycoprotein-specific quality control machinery".

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Documento generato il 20/09/20 alle ore 00:11:38