QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Peng, Y.-S. Articles by Shargo, E. Search for Related Content PubMed PubMed Citation Articles by Peng, Y.-S. Articles by Shargo, E.

Contribution of the Cytosol and Mitochondrial Pathways to Phosphoenolpyruvate Formation during Gluconeogenesis¹

Departments of Medicine and Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706

Gluconeogenesis was compared in liver slices from guinea pigs and rats to assess the significance of the different distribution patterns of phosphoenolpyruvate carboxykinase. Preferential formation of phosphoenolpyruvate in the cytosol or mitochondria was determined by addition of compounds (tryptophan, quinolinic acid, n-butylmalonate and amino oxyacetic acid) which inhibit cytosolic phosphoenolpyruvate carboxykinase or decrease the availability of substrate precursors such as malate and aspartate. During active gluconeogenesis these inhibitors are all effective. In particular, quinolinic acid at a concentration of 10 mM inhibits glucose formation about 90% in rat liver and produces a 60% inhibition in guinea pig liver. A study of avian liver phosphoenolpyruvate carboxykinase which is predominantly a mitochondrial enzyme, revealed a cytosol component during embryogenesis when there is a requirement for active gluconeogenesis. These results indicate that during maximum gluconeogenesis, the formation of phosphoenolpyruvate in the cytosol assumes a significant proportion of the carbon pathway, even in those animals which have the capacity to synthesize large amounts of this important precursor of glucose in the mitochondria.

KEY WORDS: • gluconeogenesis • phosphoenolpyruvate carboxykinase • carbon pathway

¹ This research was supported by the College of Agriculture and Life Sciences and NIH Research Grant GM-14033 and Training Grant AM-05510.

² Present Address: Department of Agricultural Biochemistry, University of Arizona, Tucson, Arizona 85700.

³ To whom correspondence should be addressed.

Manuscript received 20 April 1973.