Part of a complex composed of PLOD1, P3H3 and P3H4 that catalyzes hydroxylation of lysine residues in collagen alpha chains and is required for normal assembly and cross-linking of collagen fibrils. Required for normal bone density and normal skin stability via its role in hydroxylation of lysine residues in collagen alpha chains and in collagen fibril assembly. Interacts with PLOD1, P3H3 and PPIB. Identified in a complex with PLOD1 and P3H3. Detected in fibroblasts (at protein level) (PubMed:23959653). Detected in spleen, prostate, testis, ovary, colon, pancreas, kidney, placenta and heart (PubMed:10952778). Belongs to the leprecan family. Was originally identified in the nucleolus (PubMed:8862517). A recent publication found it only in the endoplasmic reticulum, which agrees with its biological function and the predicted signal sequence (PubMed:23959653).