Dopamine stimulated L-fucose incorporation into brain proteins is related to an increase in fucokinase activity

Abstract

Fucokinase (E.C. 2.7.1.52) activity was estimated in supernatant of homogenate from hippocampal slices. After an incubation of the slices in the presence of 0.5 mM dopamine a significant increase in the enzyme activity was observed. Under these conditions also an increase in the incorporation of [3H]fucose into hippocampal glycoproteins was observed. Thereby, the dopamine elicited changes in both fucokinase activity and fucose incorporation are similar in their time dependence. Moreover, dibutyryl-cyclic AMP led also to an increase in both fucokinase activity and sugar incorporation in hippocampal slices whereas cyclic AMP was without effect when added to the incubation mixture of the enzyme. The observed changes in fucokinase activity and its regulation by Ca2+ are discussed in terms of possible mechanisms realizing the dopamine stimulated fucosylation of rat hippocampal glycoproteins.