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Figure 2 | BMC Evolutionary Biology

Figure 2

From: Identification, distribution and molecular evolution of the pacifastin gene family in Metazoa

Figure 2

Gene structure and alternative splicing of the tcpp-1 gene (A) and the aapp-1 gene (B). The left part of the figure visualizes the tcpp-1 and aapp-1 gene structure; the silver boxes correspond to the untranslated regions, the three exons are indicated as white and grey boxes, while the horizontal connecting lines represent the intron regions. In both genes, the third exon encodes multiple PLD-related domains (grey and white boxes) and contains a stop codon (pictured in black). The right part of the figure visualizes two splicing scenarios (a and b) that finally lead to two different pacifastin-related precursor peptides. (A) Splicing of the tcpp-1 gene according to scenario aresults in a precursor polypeptide that codes for a signal peptide (white arrow), and two PLD-related domains visualized by a white and a grey box (TCPD-1 and TCPD-2, respectively). In scenario b, differential splicing of the tcpp-1 gene results in a precursor polypeptide with the same signal peptide and PLD-1 domain, but a different second pacifastin-like inhibitor domain (TCPD-3). In both precursors, the two domains are separated by putative dibasic cleavage sites (grey small bars). Full processing of both PP variants results in single-domain inhibitor peptides. (B) According to scenario a, all 7 PLD-related peptide encoding sequences of the aapp-1 gene are transcribed. In scenario bon the other hand, an additional splicing occurs in the third exon, resulting in the removal of the fourth PLD-related domain (grey box). In both precursors, all domains except PLD-1 and PLD-2 are separated by putative dibasic cleavage sites (grey small bars). Upon processing this results in the cleavage into one double-headed inhibitor peptide (PLD-1 and PLD-2) and 6 or 5 single inhibitor domain peptides.

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