Lysyl hydroxylase 3 is a multifunctional protein possessing collagen glucosyltransferase activity.

Lysyl hydroxylase (EC ) and glucosyltransferase (EC ) are enzymes involved in post-translational modifications during collagen biosynthesis. We reveal in this paper that the protein produced by the cDNA for human lysyl hydroxylase isoform 3 (LH3) has both lysyl hydroxylase and glucosyltransferase (GGT) activities. The other known lysyl hydroxylase isoforms, LH1, LH2a, and LH2b, have no GGT activity. Furthermore, antibodies recognizing the amino acid sequence of human LH3 and those against a highly purified chicken GGT partially inhibited the GGT activity. Similarly, a partial inhibition was observed when these antibodies were tested against GGT extracted from human skin fibroblasts. In vitro mutagenesis experiments demonstrate that the amino acids involved in the GGT active site differ from those required for LH3 activity.