Protein-lysine 6-oxidase that mediates the oxidation of peptidyl lysine residues to allysine in target proteins (PubMed:26954549). 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 (PubMed:26307084). Required for somite boundary formation by catalyzing oxidation of fibronectin (FN1), enhancing integrin signaling in myofibers and their adhesion to the myotendinous junction (MTJ) (PubMed:26954549). Acts as a regulator of inflammatory response by inhibiting differentiation of naive CD4(+) T-cells into T-helper Th17 or regulatory T-cells (Treg): acts by interacting with STAT3 in the nucleus and catalyzing both deacetylation and oxidation of lysine residues on STAT3, leading to disrupt STAT3 dimerization and inhibit STAT3 transcription activity (PubMed:28065600). Oxidation of lysine residues to allysine on STAT3 preferentially takes place on lysine residues that are acetylated (By similarity). Also able to catalyze deacetylation of lysine residues on STAT3 (By similarity). 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 LOXL3 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 palate: predominantly present in the palate mesenchyme and tongue (at protein level) (PubMed:26307084). In spine, expressed in the original intervertebral disk, cartilage primordia, anterior and posterior longitudinal ligaments, meninges of spinal cord, lung and heart (PubMed:26307084). In eyes, strongly expressed in the skin of the eyelid and weakly expressed in the cornea and sclera (PubMed:26307084). In lung, predominantly expressed in the pulmonary mesenchyme (PubMed:27645581). In developing muscle, expressed at myofiber ends (at protein level) (PubMed:26954549). 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. Perinatal lethality, due to impaired development of the palate shelves and abnormalities in the cartilage primordia of the thoracic vertebrae (PubMed:26307084, PubMed:26954549). Cleft palates and spinal deformities are caused by the decreased collagen cross-links in the palate and spine (PubMed:26307084). In addition, mice display a reduction in the saccular space in the lungs at 18.5 dpc (PubMed:26307084, PubMed:27645581). Lungs also show reduced lung volumes and weights and deformed and smaller thoracic cavities (PubMed:27645581). Excess elastic fibers are detected, possibly due to an increased expression of Loxl4 (PubMed:27645581). Embryos show defects in the somitic boundaries, due to defects in myofibers that anchor prematurely or overshoot to adjacent somites, and lack tension (PubMed:26954549). Splenocytes show increased number of T-cells into T-helper Th17 cells and constitutive acetylation of Stat3 (PubMed:28065600). Belongs to the lysyl oxidase family.