Lactosylceramide 4-alpha-galactosyltransferase (A4GALT)

Lactosylceramide 4-alpha-galactosyltransferase (A4GALT) is an enzyme localized predominantly in the Golgi apparatus that catalyzes the transfer of galactose from UDP-galactose to lactosylceramide, resulting in the formation of globotriaosylceramide (Gb3), also known as the P(k) antigen of the P1PK blood group system. This molecule is important for the biosynthesis of glycosphingolipids, which are key components of cell membranes and define specific blood group antigens. Gb3 also acts as a functional receptor for certain bacterial toxins, including Shiga toxin/verotoxin, which is relevant in infections like hemolytic uremic syndrome caused by Shiga-toxigenic *E. coli*. Alternative splicing and allelic variation of this enzyme underlie genetic differences in blood group antigens. The A4GALT gene is well characterized, and loss or changes in function affect both blood group antigenicity and susceptibility to bacteria that exploit Gb3 for cell entry.

Other names

Alpha 1,4-galactosyltransferaseA14GALTGlobotriaosylceramide synthaseGb3 synthaseGb3SCD77 synthaseP(k)P1PK blood group transferaseUDP-galactose:beta-D-galactosyl-beta1-R 4-alpha-D-galactosyltransferaseAlpha 1,4-galactosyltransferase (P blood group)

Not targeted directly by approved drugs. Indirect targeting mechanisms include substrate reduction or modification in glycosphingolipid metabolism.