IMMUNOLOCALIZATION OF A SCHISTOSOMA-MANSONI FACILITATED DIFFUSION GLUCOSE-TRANSPORTER TO THE BASAL, BUT NOT THE APICAL, MEMBRANES OF THE SURFACE SYNCYTIUM

Adult parasites of Schistosoma mansoni reside within vertebrate mesent eric veins where they consume immense quantities of host glucose after transporting the sugar through their surface syncytium or tegument. P reviously we obtained cDNA clones encoding two functional facilitated diffusion glucose transporter proteins expressed by S. mansoni adult w orms (Skelly et al. 1994). Antibodies specific for one transporter (SG TP1) have been generated against an extrafacial and an internal domain of the protein and used to localize the protein by light and electron microscopy. By light microscopy both antibodies stain a linear struct ure approximately 1-5 mu m from the surface of the tegument of adult m ale and female schistosomes. Electron microscopic examination of froze n thin sections show binding of the antibodies to membranes in the bas e of the tegument and not to the membranes covering the outer surface or their invaginations. Analysis of the gold distribution suggests tha t the extrafacial domain is disposed toward the interstitial space ben eath the tegument and the internal domain faces the syncytial plasm. T he localization suggests that SGTP1 may function to transport free glu cose from within the tegument and into the interstitial fluids that ba the the internal organs of these parasites.