Advanced Dental Admission Test (ADAT)

What is the primary function of fructose bisphosphatase 2 in metabolism?

1. To catalyze glycolysis

2. To initiate the TCA cycle

3. To limit the rate of gluconeogenesis

4. To stimulate glycogen breakdown

The correct answer is: To limit the rate of gluconeogenesis

Fructose bisphosphatase 2 plays a crucial role in regulating gluconeogenesis, which is the metabolic pathway responsible for producing glucose from non-carbohydrate precursors. This enzyme is particularly important in the liver and serves to convert fructose 2,6-bisphosphate to fructose 6-phosphate, thereby reducing the concentration of fructose 2,6-bisphosphate, a potent regulator of gluconeogenesis. When fructose 2,6-bisphosphate levels decrease, the stimulation of gluconeogenesis is limited, allowing for greater control over glucose production and maintaining glucose homeostasis in the body. This action effectively curbs the excessive production of glucose when it is not needed, particularly under conditions such as fasting or low carbohydrate intake, where the body must rely on gluconeogenesis for maintaining blood sugar levels. Therefore, the primary function of fructose bisphosphatase 2 is indeed to limit the rate of gluconeogenesis, ensuring that glucose is produced only when necessary for physiological needs.