Transfers N-acetylgalactosamine onto globotriaosylceramide. Plays a critical role in preimplantation stage embryonic development. globoside Gb3Cer (d18:1(4E)) + UDP-N-acetyl-alpha-D-galactosamine = globoside Gb4Cer (d18:1(4E)) + H(+) + UDP Protein modification; protein glycosylation. Belongs to the glycosyltransferase 31 family.