Lactosylceramide 4-alpha-galactosyltransferase is an enzyme that in humans is encoded by the A4GALTgene.[5][6]
The protein encoded by this gene catalyzes the transfer of galactose to lactosylceramide to form globotriaosylceramide, which has been identified as the P(k) antigen of the P blood group system. The encoded protein, which is a type II membrane protein found in the Golgi, is also required for the synthesis of the bacterial verotoxins receptor.[6]