Enables galactosylxylosylprotein 3-beta-galactosyltransferase activity. Involved in several processes, including egg-laying behavior; glycosaminoglycan biosynthetic process; and vulval development. Located in Golgi apparatus. Expressed in intestine. Human ortholog(s) of this gene implicated in Ehlers-Danlos syndrome spondylodysplastic type 2 and spondyloepimetaphyseal dysplasia with joint laxity type 1. Is an ortholog of human B3GALT6 (
beta-1,3-galactosyltransferase 6).