Beta-galactosyltransferase that transfers beta-galactose to hydroxylysine residues of type I collagen ( ). By acting on collagen glycosylation, facilitates the formation of collagen triple helix . Also involved in the biosynthesis of collagen type IV .
Subcellular locations: Endoplasmic reticulum lumen
Colocalized with PLOD3 and mannose binding lectin/MBL2.
Ubiquitous with higher levels in placenta, heart, lung and spleen.