Molecular cloning and characterization of a novel gene encoding tetraspanin of Schistosoma japonicum

In this study, a novel tetraspanin-like gene product (Sj04/ TM4) was identified. An EST named JAYN004.GYL (Gen Bank accession number AW231251) matched the Sj25 gene of Schistosoma japonicum with 97 % (539/554) identity. The longest cDNA insert (1079 bp) was obtained from the recombinant clone JAYN004.GY by PCR. Sequence analysis showed that it contains a complete open reading frame (ORF) coding for a protein of 224 amino acids with a predicted molecular mass of 25,622.58 Dalton. Alignment analysis with the entire ORF revealed that it had 93.3 % identity in 224 aa overlap % identity to Sj25/TM from S. japonicum. It also exhibited 31.4 % in 220 aa overlap and 21.1 % in 209 aa overlap, respectively to tetraspanin TE736 from S. japonicum and Sm23 antigen from S. mansoni, whose are belong to the members of tetraspanins. Analysis of amino acid sequence showed that this gene product contains all the conserved subdomains found in other members of tetraspanin superfamily. Hydropathy analysis of the deduced amino acid sequence revealed a profile very similar to those of other tetraspanins containing 4 transmembrane domains. Taken together, Sj04/TM4 is a novel gene encoding tetraspanin-like protein, or belongs to a subtype of Sj25/TM4 tetraspanin superfamily.