Fig. 1.
Chemical structure (A) and distribution of collagen in the body (B). The sequence of amino acids [Gly – X–Y]n with and without interruptions is a characteristic of the collagen family and the amino acids proline and its hydroxylated form (hydroxyproline) occupy the X and Y positions. n: number of times that this sequence appears in the protein structure. Created by the authors using BioRender.com.