Schistosoma mansoniTOR is a tetraspanning orphan receptor on the parasite surface

SUMMARYA trispanning orphan receptor (TOR) has been described inSchistosoma haematobiumandS. mansoni. Here we report the complete molecular organization of theS. mansoniTOR gene, also known as SmCRIT (complement C2 receptor inhibitor trispanning). The SmTOR gene consists of 4 exons and 3 introns as shown by cloning the single exons fromS. mansonigenomic DNA and the corresponding cDNA from the larval stage (cercaria) and the adult worm. The SmTOR ORF consists of 1260 bp and is longer than previously reported, with a fourth trans-membrane domain (proposed new name: Tetraspanning Orphan Receptor) and with, however, an unchanged C2-binding domain on the extracellular domain 1 (ed1). This domain differs inS. japonicum. A protein at the approximate expected molecular weight (55 kDa) was detected in adult worm extracts with polyclonal and monoclonal antibodies, and was found to be expressed on the tegumental surface of cercariae.