Protein-lysine 6-oxidase that mediates the oxidation of peptidyl lysine residues to allysine in target proteins (By similarity). Catalyzes the post-translational oxidative deamination of peptidyl lysine residues in precursors of elastin and different types of collagens, a prerequisite in the formation of cross-links between collagens and elastin (By similarity). Can mediate oxidation of lysine residues that are acetylated (By similarity). Also able to catalyze deacetylation of lysine residues (By similarity). Required for maturation of neural crest derived cartilage elements (PubMed:21244857). H2O + L-lysyl-[protein] + O2 = (S)-2-amino-6-oxohexanoyl-[protein] + H2O2 + NH4(+) H2O + N(6)-acetyl-L-lysyl-[protein] + O2 = (S)-2-amino-6-oxohexanoyl-[protein] + acetamide + H2O2 Contains 1 lysine tyrosylquinone. It is unclear how loxl3b is both intracellular (cytoplasmic and nuclear) and extracellular: it contains a clear signal sequence and is predicted to localize in the extracellular medium. However, the intracellular location is clearly reported and at least another protein of the family (loxl2) also has intracellular and extracellular localization despite the presence of a signal sequence. Expressed in the notochord from the 10 somite stage. Highly expressed in head mesenchyme and developing cartilages that will form the craniofacial skeleton. The lysine tyrosylquinone cross-link (LTQ) is generated by condensation of the epsilon-amino group of a lysine with a topaquinone produced by oxidation of tyrosine. Craniofacial defects. Cartilage elements embryos do not mature and chondrocyte morphology and extracellular matrix are affected. Belongs to the lysyl oxidase family. Contaminating sequence. Potential poly-A sequence.