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Enzymatic characterization of four new mutations in the glucose-6 phosphatase (G6PC) gene which cause glycogen storage disease type 1a

Published online by Cambridge University Press:  01 March 1999

N. BRUNI
Affiliation:
Institut National de la Santé et de la Recherche Médicale (Unité 449), Faculté de Médecine R. T. H. Laennec, 69372 Lyon Cédex 08, France
F. RAJAS
Affiliation:
Institut National de la Santé et de la Recherche Médicale (Unité 449), Faculté de Médecine R. T. H. Laennec, 69372 Lyon Cédex 08, France
S. MONTANO
Affiliation:
Institut National de la Santé et de la Recherche Médicale (Unité 449), Faculté de Médecine R. T. H. Laennec, 69372 Lyon Cédex 08, France
F. CHEVALIER-PORST
Affiliation:
Centre d'Etudes des Maladies Métaboliques, Hôpital Debrousse, 69322 Lyon Cédex 05, France
I. MAIRE
Affiliation:
Centre d'Etudes des Maladies Métaboliques, Hôpital Debrousse, 69322 Lyon Cédex 05, France
G. MITHIEUX
Affiliation:
Institut National de la Santé et de la Recherche Médicale (Unité 449), Faculté de Médecine R. T. H. Laennec, 69372 Lyon Cédex 08, France
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Abstract

Glycogen storage disease type 1a (GSD1a) is caused by mutations in the gene of glucose-6 phosphatase (G6PC), encoding the last enzyme of gluconeogenesis and glycogenolysis. To study the effect of mutations previously identified, but not yet enzymatically characterized, in French GSD1a patients, we used an in vitro expression system of the human glucose-6 phosphatase (hGlc6Pase) cDNA. Wild type hGlc6Pase expressed in COS-7 cells exhibited kinetic features comparable to microsomal Glc6Pase from normal human liver and kidney. Four new mutations inducing aminoacid changes in the coding sequence, e.g. W77R, A124T, G184E and L211P, were inserted into the Glc6Pase cDNA by site-directed mutagenesis, and studied after transient expression in COS-7 cells. All four mutations totally abolished Glc6Pase activity.

Type
Research Article
Copyright
© University College London 1999

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