Collagen Gene

**Semantic type:** Gene or Genome

**Definition:** Collagen Genes encode different forms of Collagen, the principle fibrous protein of connective tissue, all consisting of triple helix alpha-polypeptide chains. Collagen is differentiated from other fibrous proteins by its content of proline, hydroxyproline, and hydroxylysine; by its absence of tryptophan; and by its high content of polar groups. Hydroxyproline residues likely promote the triple helical fibrous structure of collagen. (NCI)