This entry represents prolyl 3-hydroxylase, including prolyl 3-hydroxylase catalyses 1-3 (P3H1-3) from humans. P3H1, also known as leprecan-1, is responsible for converting proline to 3-hydroxyproline (3Hyp) in type I collagen. P3H2 is responsible for 3-hydroxylating multiple proline sites in collagen types I, II, IV, and V []. However, P3H3 is not required for normal prolyl 3-hydroxylation on collagen chains [].