The present invention relates to non-mammalian ²-1,4-galactosyltransferases that can be used in their wild-type or in modified forms. The invention further relates to transformed plants and plant cells expressing non-mammalian ²-1,4-galactosyltransferases and methods to produce glycoproteins with altered and preferably mammalian-type glycosylation. The invention additionally provides nucleic acid molecules and expression vectors of non-mammalian ²-1,4-galactosyltransferases.