These domains vary in length and composition and provide flexibility and additional binding sites for other components of the extracellular matrix. There are eight known types of FACIT collagens: collagens IX, XII, XIV, XVI, XIX, XXI, and XXII.
The various domains have differing lengths and compositions, providing adaptability and extra binding points for other elements in the extracellular matrix. There exist eight distinct types of FACIT collagens: collagens IX, XII, XIV, XVI, XIX, XXI, and XXII.