key term - Glucose-6-phosphatase

Definition

Glucose-6-phosphatase is an enzyme that catalyzes the hydrolysis of glucose-6-phosphate to glucose and inorganic phosphate, playing a crucial role in glucose homeostasis. This enzyme is primarily found in the liver and kidneys, where it facilitates the release of glucose into the bloodstream during fasting states, thus contributing to maintaining blood sugar levels.

5 Must Know Facts For Your Next Test

1. Glucose-6-phosphatase is a key enzyme in gluconeogenesis, as it allows for the conversion of glucose-6-phosphate into free glucose, making it available for use by other tissues.
2. This enzyme is predominantly located in the endoplasmic reticulum of liver and kidney cells, which are crucial for blood sugar regulation.
3. Deficiency in glucose-6-phosphatase can lead to glycogen storage diseases, such as von Gierke disease, characterized by hypoglycemia and accumulation of glycogen in tissues.
4. The activity of glucose-6-phosphatase is increased during fasting states when blood glucose levels drop, allowing for gluconeogenesis to maintain adequate glucose supply.
5. The regulation of this enzyme is tightly linked to hormonal signals, particularly glucagon and epinephrine, which stimulate its activity to promote gluconeogenesis and glycogenolysis.

Review Questions

• How does glucose-6-phosphatase contribute to maintaining blood glucose levels during fasting?
  • During fasting, blood glucose levels drop, prompting the liver to initiate gluconeogenesis and glycogenolysis. Glucose-6-phosphatase plays a critical role by converting glucose-6-phosphate, derived from these processes, into free glucose. This release of glucose into the bloodstream helps maintain adequate energy levels for other tissues and organs, ensuring that vital functions continue during periods without food intake.
• Discuss the impact of hormonal regulation on the activity of glucose-6-phosphatase and its significance in carbohydrate metabolism.
  • Hormonal regulation significantly influences the activity of glucose-6-phosphatase. Glucagon and epinephrine stimulate this enzyme's activity during fasting or stress conditions, promoting gluconeogenesis and glycogenolysis. In contrast, insulin has an inhibitory effect on its activity, leading to decreased gluconeogenesis when blood glucose levels are sufficient. This delicate balance ensures that carbohydrate metabolism is tightly regulated, maintaining blood sugar homeostasis in response to various physiological states.
• Evaluate the implications of a deficiency in glucose-6-phosphatase on metabolic health and its broader consequences.
  • A deficiency in glucose-6-phosphatase can lead to serious metabolic disorders such as von Gierke disease, which results in severe hypoglycemia and excessive glycogen accumulation in liver and kidney tissues. The inability to convert glucose-6-phosphate into free glucose disrupts normal energy production during fasting states and can lead to symptoms like lethargy, growth impairment, and developmental issues. This condition highlights the importance of glucose-6-phosphatase in overall metabolic health and its critical role in maintaining energy balance within the body.

Related terms

Glycogenolysis:

The process of breaking down glycogen into glucose-1-phosphate and glucose, which can then be converted to glucose-6-phosphate.

Insulin: A hormone produced by the pancreas that lowers blood glucose levels by promoting the uptake of glucose by tissues and inhibiting gluconeogenesis.

Gluconeogenesis: The metabolic pathway that results in the generation of glucose from non-carbohydrate substrates, mainly occurring in the liver.