Glucose 6-phosphate transport has been well characterized in liver microsomes. The transport is required for the functioning of the glucose-6-phosphatase enzyme that is situated in the lumen of the hepatic endoplasmic reticulum. The genetic deficiency of the glucose 6-phosphate transport activity causes a severe metabolic disease termed type 1b glycogen storage disease. The cDNA encoding a liver transporter for glucose 6-phosphate was cloned and was found to be mutated in patients suffering from glycogen storage disease 1b. While related mRNAs have been described in liver and other tissues, the encoded protein(s) has not been immunologically characterized yet. In the present study, we report (using antibodies against three different peptides of the predicted amino acid sequence) that a major protein encoded by the glucose 6-phosphate transporter gene is expressed in the endoplasmic reticulum membranes of rat and human liver. The protein has an apparent molecular mass of approx. 33 kDa using SDS/PAGE, but several lines of evidence indicate that its real molecular mass is 46 kDa, as expected. The glucose 6-phosphate transporter protein was also immunodetected in kidney microsomes, but not in microsomes derived from human fibrocytes, rat spleen and lung, and a variety of cell lines. Moreover, little or no expression of the glucose 6-phosphate transporter protein was found in liver microsomes obtained from three glycogen storage disease 1b patients, even bearing mutations that do not directly interfere with protein translation, which can be explained by a (proteasome-mediated) degradation of the mutated transporter.
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Research Article|
June 21 2005
Immunodetection of the expression of microsomal proteins encoded by the glucose 6-phosphate transporter gene
Silvia SENESI;
Silvia SENESI
*Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
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Paola MARCOLONGO;
Paola MARCOLONGO
*Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
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Tamas KARDON;
Tamas KARDON
†Department of Medical Chemistry, Semmelweis University, 1444-Budapest, Hungary
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Giovanna BUCCI;
Giovanna BUCCI
*Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
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Andrey SUKHODUB;
Andrey SUKHODUB
‡Division of Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, U.K.
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Ann BURCHELL;
Ann BURCHELL
‡Division of Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, U.K.
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Angelo BENEDETTI;
Angelo BENEDETTI
1
*Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
1To whom correspondence should be addressed (email benedetti@unisi.it).
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Rosella FULCERI
Rosella FULCERI
*Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
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Publisher: Portland Press Ltd
Received:
February 03 2005
Revision Received:
March 02 2005
Accepted:
March 10 2005
Accepted Manuscript online:
March 10 2005
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2005
Biochem J (2005) 389 (1): 57–62.
Article history
Received:
February 03 2005
Revision Received:
March 02 2005
Accepted:
March 10 2005
Accepted Manuscript online:
March 10 2005
Citation
Silvia SENESI, Paola MARCOLONGO, Tamas KARDON, Giovanna BUCCI, Andrey SUKHODUB, Ann BURCHELL, Angelo BENEDETTI, Rosella FULCERI; Immunodetection of the expression of microsomal proteins encoded by the glucose 6-phosphate transporter gene. Biochem J 1 July 2005; 389 (1): 57–62. doi: https://doi.org/10.1042/BJ20050213
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