Abstract
There seems to exist a relatively low similarity between the amino acid sequences of the testis and milk, β-1, 4-galactosyltransf erase gene products. However, the predicted higher structures of testis and milk β-1, 4-galactosyltransferase proteins revealed a highly significant similarity in the regions required for enzymatic activities. Testis β-1, 4-galactosyltransferase protein contained a WD repeat similar to the motif of the G protein β subunit type I and a Zn-finger motif at the N- and C-terminal portions of the protein, respectively. Phylogenetic analysis of glycosyltransferase proteins revealed that the ancestral gene of testis and milk β-1, 4-galactosyltransferases and β-l, 3-galactosyltransferase evolved into three different destinations at about the same time on an evolutionary scale.
