Forms hydroxylysine residues in -Xaa-Lys-Gly- sequences in collagens. These hydroxylysines serve as sites of attachment for carbohydrate units and are essential for the stability of the intermolecular collagen cross-links. 2-oxoglutarate + L-lysyl-[collagen] + O2 = (5R)-5-hydroxy-L-lysyl-[collagen] + CO2 + succinate Homodimer. Highly expressed in pancreas and muscle. Isoform 1 and isoform 2 are expressed in the majority of the examined cell types. Isoform 2 is specifically expressed in skin, lung, dura and aorta. The disease is caused by variants affecting the gene represented in this entry. The molecular defect leading to Bruck syndrome is an aberrant cross-linking of bone collagen, due to underhydroxylation of lysine residues within the telopeptides of type I collagen, whereas the lysine residues in the triple helix are normal. Extended N-terminus. Procollagen-lysine,2-oxoglutarate 5-dioxygenase 2 (PLOD2)