Schistosoma mansoni: the glucose transport protein SGTP4 is present in tegumental multilamellar bodies, discoid bodies, and the surface lipid bilayers.

Schistosomes metabolize large quantities of glucose obtained from the host serum by facilitated diffusion through the tegument. Here we have used rabbit antibodies affinity purified against the carboxyl terminus of a facilitated glucose transporter, SGTP4, to localize the antigen in both schistosomula and adults. By ultrastructural immunocytochemical analysis, SGTP4 was localized to both lipid bilayers that cover the tegumental surface of adults and schistosomula. In the inner bilayer of adults, SGTP4 was apparently oriented with the carboxyl terminus on the internal side of the bilayer. SGTP4 was also present in the discoid and multilamellar bodies in adults and the membranous bodies in schistosomula. Finally, the affinity purified antibodies against SGTP4 bound nonspecifically to the head glands and postacetabular glands in schistosomula. The localization of the antigen in the two surface lipid bilayers suggests that SGTP4 may be responsible for transporting glucose from mammalian host serum into the tegument.