Gangliosides are formed from a glycosphingolipid combined with one or more sialic acids at the oligosaccharide chain. They are anchored at the outer surface of the plasma membrane where they pack densely with cholesterol to form lipid microdomains that modulate both intra- and inter-cellular signaling events. Ganglioside GT1b is a trisialoganglioside that is characterized by having two sialic residues linked to the inner galactose unit. Ganglioside GT1b has inhibitory effects towards human humoral immune responses. At 0.1-10 μM, it can inhibit spontaneous IgG, IgM, and IgA production by human peripheral blood mononuclear cells. It has also been proposed as a host cell receptor for the Merkel cell polyomavirus and as a means to enable the initiation of an infection leading to Merkel cell carcinoma.
