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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
1
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pubmed:dateCreated |
1999-4-22
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pubmed:abstractText |
Glycogenin is a dimeric self-glucosylating protein involved in the initiation phase of glycogen biosynthesis. As an enzyme, glycogenin has the unusual property of transferring glucose residues from UDP-glucose to itself, forming an alpha-1,4-glycan of around 10 residues attached to Tyr194. Whether this self-glucosylation reaction is inter- or intramolecular has been debated. We used site-directed mutagenesis of recombinant rabbit muscle glycogenin-1 to address this question. Mutation of highly conserved Lys85 to Gln generated a glycogenin mutant (K85Q) that had only 1-2% of the self-glucosylating activity of wild-type enzyme. Consistent with previous work, mutation of Tyr194 to Phe in a GST-fusion protein yielded a mutant, Y194F, that was catalytically active but incapable of self-glucosylation. The Y194F mutant was able to glucosylate the K85Q mutant. However, there was an initial lag in the self-glucosylation reaction that was abolished by preincubation of the two mutant proteins. The interaction between glycogenin subunits was relatively weak, with a dissociation constant inferred from kinetic experiments of around 2 microM. We propose a model for the glucosylation of K85Q by Y194F in which mixing of the proteins is followed by rate-limiting formation of a species containing both subunit types. The results provide the most direct evidence to date that the self-glucosylation of glycogenin involves an inter-subunit reaction.
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pubmed:grant |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Calmodulin-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Glucose,
http://linkedlifedata.com/resource/pubmed/chemical/Glucosyltransferases,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamine,
http://linkedlifedata.com/resource/pubmed/chemical/Glutathione Transferase,
http://linkedlifedata.com/resource/pubmed/chemical/Glycogen,
http://linkedlifedata.com/resource/pubmed/chemical/Glycoproteins,
http://linkedlifedata.com/resource/pubmed/chemical/Lysine,
http://linkedlifedata.com/resource/pubmed/chemical/Phenylalanine,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Fusion Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Tyrosine,
http://linkedlifedata.com/resource/pubmed/chemical/glycogenin
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0003-9861
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pubmed:author |
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pubmed:copyrightInfo |
Copyright 1999 Academic Press.
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pubmed:issnType |
Print
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pubmed:day |
1
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pubmed:volume |
363
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
163-70
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:10049511-Amino Acid Substitution,
pubmed-meshheading:10049511-Animals,
pubmed-meshheading:10049511-Calmodulin-Binding Proteins,
pubmed-meshheading:10049511-Catalysis,
pubmed-meshheading:10049511-Electrophoresis, Polyacrylamide Gel,
pubmed-meshheading:10049511-Escherichia coli,
pubmed-meshheading:10049511-Glucose,
pubmed-meshheading:10049511-Glucosyltransferases,
pubmed-meshheading:10049511-Glutamine,
pubmed-meshheading:10049511-Glutathione Transferase,
pubmed-meshheading:10049511-Glycogen,
pubmed-meshheading:10049511-Glycoproteins,
pubmed-meshheading:10049511-Glycosylation,
pubmed-meshheading:10049511-Lysine,
pubmed-meshheading:10049511-Molecular Weight,
pubmed-meshheading:10049511-Mutagenesis, Site-Directed,
pubmed-meshheading:10049511-Phenylalanine,
pubmed-meshheading:10049511-Rabbits,
pubmed-meshheading:10049511-Recombinant Fusion Proteins,
pubmed-meshheading:10049511-Recombinant Proteins,
pubmed-meshheading:10049511-Tyrosine
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pubmed:year |
1999
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pubmed:articleTitle |
Self-glucosylation of glycogenin, the initiator of glycogen biosynthesis, involves an inter-subunit reaction.
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pubmed:affiliation |
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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