It has been shown that gangliosides exert an influence on serotonin (5
-HT) binding and uptake by human platelets. The effect depends on gang
lioside structure. In particular, GT1b increases the number of 5-HT bi
nding sites by 40 to 60%, and GM1, GM3 and GD3 decrease it by 20 to 40
%. None of the gangliosides tested influences the affinity of the 5-HT
binding sites with K-D = 60 +/- 10 nM. It has been found that loading
platelets with GT1b increases the rate of 5-HT uptake and increases t
he capacity of platelets for this monoamine. It is concluded that gang
liosides incorporated into platelet membranes influence the number of
5-HT binding sites on the serotonin transporter.