Enables UDP-galactose:beta-N-acetylglucosamine beta-1,3-galactosyltransferase activity. Acts upstream of or within oligosaccharide biosynthetic process. Predicted to be located in Golgi apparatus and membrane. Predicted to be integral component of membrane. Predicted to be active in Golgi membrane. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; hemolymphoid system; and sensory organ. Orthologous to human B3GALNT1 (beta-1,3-N-acetylgalactosaminyltransferase 1 (globoside blood group)). [provided by Alliance of Genome Resources, Apr 2022]