title: Schistosoma TOR (trispanning orphan receptor), a novel, antigenic surface receptor of the blood-dwelling, Schistosoma parasite.
abstract: Sh-TOR is a novel, putative three transmembrane domain receptor of Schistosoma haematobium, which has no extensive homology to any other known protein. The 0.86 kb open reading frame was found to encode a novel protein, 286 amino acids long and of 32 kDa. It was shown that Sh-TOR can be phosphorylated on tyrosine and the protein sequence reveals a long cytoplasmic tail with several consensus phosphorylation sites for enzymes which characteristically associate with membrane receptors. The proposed topology of Sh-TOR, based on antibody recognition of transfected Sh-TOR, predicts that the amino terminus is extracellular and the carboxyl terminus intracellular. Sh-TOR is a non-glycosylated protein found in the surface tegumental plasma membrane, and tegumental surface pits of adult schistosomes. The 1.35 kb transcript was most highly expressed in the larval stage, which is more susceptible to immune attack. A TOR homologue from Schistosoma mansoni is also described. A homologue from Trypanosoma cruzi, another human parasite was also isolated, but not from the free-living nematode Caenorhabditis elegans. Recombinant Sh-TOR is specifically recognised by a passively protective serum, from baboons vaccinated with irradiated Schistosoma parasite. Together with its surface location, this means that Sh-TOR is also a potential vaccine candidate molecule.
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK. jinal@globalnet.co.uk
authors.forename: J M
authors.initials: JM
authors.lastname: Inal
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000947:Antigens, Helminth; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D015870:Gene Expression; D015723:Gene Library; D015801:Helminth Proteins; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D012548:Schistosoma haematobium / Q000235:genetics / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
chemical_list: D000906:Antibodies; D000947:Antigens, Helminth; D015801:Helminth Proteins; D011956:Receptors, Cell Surface; C120046:TM3 protein, Schistosoma