Mysteries of the collagen triple helix.

The collagen triple helix is one of the structurally simplest protein motifs that still holds a lot of secrets. The Gly-X-Y repeat is a business card of collagens, where Gly is required for the tight packing of three helices into a superhelix and X and Y residues are important for stabilizing the triple helix and communicating with the world. On its way to a functional molecule, collagen sequences undergo unique post-translational modifications inside and outside of the cell. Moreover, folding and secretion of collagens require specific proteins and mechanisms. Cracking the collagen triple helix codes opens up opportunities for curing associated diseases and developing new biomaterials. Here, we summarized my journey through some mysteries of the collagen triple helix and point out key unaddressed questions and problems for other researchers to pursue.