Focusyltransferase 7 (FUT7) is a Golgi stack membrane protein. It catalyzes the final fucosylation step in the synthesis of Lewis antigens, resulting in the production of the specific glycosylated product sialyl Lewis X (sLeX). FUT7 is involved in catalyzing the α-1,3 glycosidic bond, which is crucial for sialyl Lewis X antigen expression.