Proline is an essential amino acid that is involved in many important biological processes. It is a hydrophobic amino acid, meaning it is not soluble in water. Proline is found in proteins and is important for the structure and stability of proteins. It is also involved in the formation of collagen, which is a major component of connective tissue. Proline is also involved in the regulation of gene expression and is important for cell growth and development. It is also involved in the metabolism of carbohydrates and fats. Proline is found in many foods, including meat, dairy, eggs, and some vegetables. 