C. Breton et al., SEQUENCE-FUNCTION RELATIONSHIPS OF PROKARYOTIC AND EUKARYOTIC GALACTOSYLTRANSFERASES, Journal of Biochemistry, 123(6), 1998, pp. 1000-1009
Galactosyltransferases are enzymes which transfer galactose from UDP-G
al to various accepters with either retention of the anomeric configur
ation to form alpha 1,2-, alpha 1,3-, alpha 1,4-, and alpha 1,6-linkag
es, or inversion of the anomeric configuration to form beta 1,3-, beta
1,4-, and beta 1-ceramide linkages. During the last few years, severa
l (c)DNA sequences coding for galactosyltransferases became available.
We have retrieved these sequences and conducted sequence similarity s
tudies. On the basis of both the nature of the reaction catalyzed and
the protein sequence identity, these enzymes can be classified into tw
elve groups. Using a sensitive graphics method for protein comparison,
conserved structural features were found in some of the galactosyltra
nsferase groups, and other classes of glycosyltransferases, resulting
in the definition of five families. The lengths and locations of the c
onserved regions as well as the invariant residues are described for e
ach family, In addition, the DxD motif that may be important for subst
rate recognition and/or catalysis is demonstrated to occur in all fami
lies but one.