Cloning and characterization of a fifth human lysyl oxidase isoenzyme: the third member of the lysyl oxidase-related subfamily with four scavenger receptor cysteine-rich domains.

We report the complete cDNA sequence of the human lysyl oxidase-like 4 (LOXL4) gene, a new member of the lysyl oxidase (LO) gene family. The predicted polypeptide is 756 amino acids long, including a 24-residue signal peptide. The C-terminal region contains a LO domain similar to those of LOX, LOXL, LOXL2 and LOXL3. The N-terminal region has four subregions similar to scavenger receptor cysteine-rich domains that are highly conserved with LOXL2 and LOXL3. The LOXL4 mRNA is approximately 4 kb in size and is expressed in many tissues, the highest levels among the tissues studied being in the skeletal muscle, testis and pancreas. Recombinant LOXL4 expressed in HT-1080 cells was secreted into the culture medium with no evident proteolytic processing.