As the name implies, the protein in this puzzle is a component of collagen, a protein found in connective tissue. The puzzle protein is not a complete collagen, but the "Kunitz-type domain from the alpha3 chain of human type VI collagen".
The puzzle protein has 55 segments with the sequence:
This sequence is found in this Protein Data Bank entry:
The puzzle protein can have three disulfide bridges, identified in 2KNT as 5-55, 14-38, and 30-51. In recent visits to this puzzle, each bridge is awarded a bonus of 250 points. Since the matching PDB entries start with an additional residue, subtract one to get the Foldit segment number.
The recipe Bridge Wiggle v 1.2.1 - Brow42 accepts the bridges in this format:
4,54 13,37 29,50
This puzzle does not have any ligands.
This puzzle has a single chain.
See players' solutions from previous visits this puzzle: