TGR variants in Schistosoma spp. Amino acid sequence alignment of S. japonicum (denoted as SCHJA) and S. mansoni (denoted as SCHMA) TGR variants. Variant 1 (v1) encodes a TGR with a mitochondrial signal peptide, variant 2 (v2) encodes a TGR with shorter leader peptide with no topology prediction, and variant 3 (v3) encodes a cytosolic TGR. B. Nucleotide sequence alignment of ESTs encoding S. japonicum and S. mansoni TGR variants; the sequence of SCHMA_v1 was deduced from the corresponding TGR gene. C. Nucleotide genomic sequence of S. mansoni and S. japonicum TGRs. The sequence corresponds to the end of the first exon, the first intron (indicated by italics) and the beginning of the second exon. GT and AG donor and acceptor splice sites of intron I, whose splicing generates variant 1, are shown underlined in lower case. Underlined in capital letters and in italics is shown a presumptive leaky GT donor splice site present in exon I, that, if spliced, gives rise to variant 2. Sequences of variant 3 were retrieved from translated full-cDNAs deposited in Genebank (accession Numbers gb|AAK85233.1|AF395822_1, gb|AAW25951.1), sequences of variants 1 and 2 correspond to ESTs deposited in Genebank (gb|BU801474.1 for Sja variant 1, gb|BU791993.1 and gb|CV688441.1 for Sja2, and gb|CD202891.1 for Sma variant 2). D. Proposed model of how Schistosoma mRNA variants would be generated. From TGR gene, two primary transcripts would be synthesized from alternative transcription initiation sites: core promoter and a putative intron I promoter. The transcript derived form the core promoter would give rise to two different mRNAs by alternative transcript processing.