How does the body make glucose from protein?

The process of converting protein into glucose is known as gluconeogenesis. It occurs primarily in the liver and, to a lesser extent, in the kidneys. Here is a general overview of how the body makes glucose from protein:

1. Protein Breakdown: When the body needs glucose but dietary carbohydrate intake is insufficient, it breaks down stored protein, primarily from skeletal muscle. This process, known as proteolysis, releases amino acids into the bloodstream.

2. Amino Acid Deamination: The amino acids released from protein breakdown undergo a process called deamination, removing their amino group. This process occurs in the liver and results in the production of ammonia and keto acids, which are carbon skeletons derived from amino acids.

3. Formation of Pyruvate: The keto acids generated from amino acid deamination can be converted into pyruvate through a series of chemical reactions. Pyruvate is a key intermediate in cellular metabolism and can enter the gluconeogenesis pathway.

4. Gluconeogenesis: Gluconeogenesis is a series of enzymatic reactions that converts non-carbohydrate molecules into glucose. Pyruvate, derived from amino acids, can enter this pathway and be converted into glucose through a set of 11 reactions. The process involves the formation of various intermediates, including oxaloacetate, phosphoenolpyruvate, and fructose 1,6-bisphosphate.

5. Glucose Release: Once glucose is synthesized through gluconeogenesis, it can be released into the bloodstream to maintain normal blood glucose levels. The liver plays a significant role in releasing glucose into the bloodstream when dietary glucose is limited.

It's important to note that gluconeogenesis is a regulated process, and the body tightly controls it to ensure that protein is not broken down excessively. Factors like insulin levels, hormone signaling, and energy balance influence the rate of gluconeogenesis.