The kinetics of the inhibition of rat brain synaptosomal dopamine uptake by manganous ions [proceedings].

~ [ ~ H l F u c o s e (1.4pCi/mg of synaptosomal protein: sp. radioactivity 6.7Ci/mmol) and various concentrations of L-fucose were incubated with Ficoll-prepared synaptosomes. After lysis, fraction S was assayed for protein content and radioactivity. 33 nmol/mg of protein. Therefore under the conditions adopted in the present study the fucose turnover in synaptosomal fucosylglycoprotein appears to occur every 47 h. The use of pinched-off synaptosomes as a model system for the study of nerve-terminal function has been criticized because of contamination by other subcellular particles, which include mitochondria and microsomal fraction. To assess if fucosylation of fractions S and I had resulted, both mitochondria prepared from the Ficoll gradient and microsomal fraction from the lOOOOg pellet were incubated with ~-('HIfucose. In both instances negligible amounts of IH were found to be incorporated. Therefore it is concluded that synthesis of fucosylglycoprotein is a feature of nerve terminals.