Precursors for gluconeogenesis

Lesson 18 : Gluconeogenesis

Precursors for gluconeogenesis

  1. Lactate: Anaerobic respiration of pyruvate.

  2. Amino acids:

  3. fg

  4. Glycerol
  5. g

    This process occurs during periods of fasting, starvation, or intense exercise and is highly endergonic. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type II diabetes, such as metformin, which inhibit glucose formation and stimulate glucose uptake by cells

    Several non-carbohydrate carbon substrates can enter the gluconeogenesis pathway. One common substrate is lactic acid, formed during anaerobic respiration in skeletal muscle. Lactate is transported back to the liver where it is converted into pyruvate and then be used to generate glucose. All citric acid cycle intermediates, through conversion to oxaloacetate, amino acids other than lysine or leucine, and glycerol can also function as substrates for gluconeogenesis. Glycerol, which is a part of all triacylglycerols, can also be used in gluconeogenesis.

    Comparing the energy expenditure for gluconeogenesis with the gain from glycolysis clearly shows that it costs more to generate glucose from internal metabolites than to break it down once glucose is inside the cell:

    1 Glucose ? 2 Lactate + 2 ATP

    2 Lactate + 6 ATP ? 1 Glucose

Last modified: Saturday, 21 January 2012, 6:00 AM