Ved in catalytically functional PLA2, but in many Viperidae myotoxic PLA
Ved in catalytically functional PLA2, but in many Viperidae myotoxic PLA2s, it is substituted by a lysine residue (Lys49) [22]. No such latter form was detected in this transcriptome. It was interesting to note that the singlet cluster MCOR0404S, shows a peculiar sequence due to a 114-bp insertion in position 110, within the mature protein (Figure 3). Comparing the sequence of this insertion against databases, it is possible to see that it corresponds to the last 114 bp of the fourth intron of some elapidic PLA2 genes, such as that from Laticauda semifasciata [23]. These introns 4 of PLA2s usually have around 500 bp, but only 114 bp are present in the insertion of MCOR0404S cDNA. Assuming a conserved gene structure of PLA2 genes among species, this insertion may represent possible incompletePage 4 of(page number not for citation purposes)BMC Genomics 2009, 10:http://www.biomedcentral.com/1471-2164/10/Figure Segment3of PLA2 clusters, showing the presence of a 114 bp insertion in MCOR0404S Segment of PLA2 clusters, showing the presence of a 114 bp insertion in MCOR0404S. This inserted sequence is very similar to the last 114 bp of the fourth intron of PLA2 gene from several snakes, including L. semifasciata (aligned above the insertion), and is delimited by the canonic GT and AG in intron/exon junctions.splicing of PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27693494 the transcript, since a 3′ portion of the intron remained attached to the mRNA. In fact, the insertion starts with the dinucleotide GT and PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28607003 ends with AG, precisely the canonic sequence for intron/exon junctions (Figure 3). Besides, the insertion of 114 bp is a multiple of 3, and hence, it corresponds to 38 codons (without stop codons). This allows, after the insertion, the continuity of the reading frame, keeping the original C-terminal region. Although this insertion could originate from a random mistake in the splicing process, the absence of stop codons or cysteine residues (which would destabilize the structure) and the fact that it keeps the translational phase are indicative that it could result in a new protein product. Nevertheless, the analysis of the inserted amino acid sequence does not display similarity with any known domain. This is another example of indels frequently observed in toxin cDNAs [24].C-type Lectins C-type lectins are non-enzymatic proteins present in the venom of snakes of all families. Like plant lectins, some of the venom lectins are able to bind to carbohydrates. In the presence of Ca2+, the C-type lectins begin several biological processes, such as adhesion, agglutination, endocytosis and neutralization of the pathogen. The lectins could be divided into seven different groups according to their structural characteristics [25]. The C-type lectins that have lost their capability of purchase PD325901 binding to carbohydrates are called lectin-like, because they still maintain the structural characteristics in common with true lectins. Venom lectins may act as agonists or sometimes antagonists in platelet aggregation and affect thrombosis and homeostasis by activating and inhibiting specific receptors in platelet membranes [26].The C-type lectins found here were also abundant toxins. Sixty-five clones show similarity with these proteins and were grouped into 13 clusters, representing approximately 5 of the total transcripts expressed in the tissue. Many of the clusters correspond to full-lengths ORFs that could be aligned with other C-type lectins from venom [see Additional file 2]. C-type lectins are ubiquitous compo.
