A novel gene defining a novel enzyme UDP-Galactose: .beta.-D-Galactose-R 4-.alpha.-D-galactosyltransferase, termed .alpha.4Gal-T1, with unique enzymatic properties is disclosed. The invention discloses isolated DNA molecules and DNA constructs encoding .alpha.4Gal-T1 and derivatives thereof by way of amino acid deletion, substitution or insertion exhibiting .alpha.4Gal-T1 activity, as well as cloning and expression vectors including such DNA, cells transfected with vectors, and recombinant methods for providing .alpha.4Gal-T1. The enzyme .alpha.4Gal-T1 and .alpha.4Gal-active derivatives thereof are disclosed. Further, the invention discloses methods of obtaining .alpha.1, 4galactosyl glycosylated glycosphingolipids by use of an enzymatically active .alpha.4Gal-T1 protein thereof or by using cells stably transfected with a vector including DNA encoding an enzymatically active .alpha.4Gal-T1 protein as an expression system for recombinant production of such glycosphingolipids. Also a method for the identification of DNA sequence variations in the .alpha.4Gal-T1-coding exon by PCR, and detecting the presence of DNA sequence variation, are disclosed.