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. 2013 Apr 20;242(7):861–873. doi: 10.1002/dvdy.23979

Fig. 2.

Fig. 2

Genomic and transcript analysis of the semaphorin2b gene A: A schematic of the semaphorin2b locus. The horizontal line represents the genomic region located at 53C1, with the small vertical lines marking 4-kilobase intervals. Rectangles located beneath the line represent exons defined by cDNA analysis with untranslated regions shown with open rectangles and coding regions shown with black rectangles. The two black arrows represent points of transcription initiation as defined by cDNA analysis. The green triangle represents the insertion point of EP2056 and ME722 and the green arrow shows the direction of misexpression transcription initiated by Gal4. The red triangle represents the insertion point of the f02042 piggyBac element. B: A lineup of the predicted Sema2a and Sema2b proteins. Potential signal sequence cleavage sites are shown with black arrowheads. Identical amino acids are shaded grey and similar amino acids are shaded green. The position of the semaphorin domain is marked with a red line and the position of the PSI domain is shown with a blue line. The location of the insertion point of f02042 in the genome relative to the primary amino acid sequence of sema2b is shown with a red triangle. RT-PCR analysis suggested the presence of several splice isoforms with altered amino acid sequence of the Sema2b protein. The effects of three such isoforms that were used to generate UAS constructs are shown here. The asterisk denotes the last amino acid in the predicted protein that matches the wild-type sequence before it diverges. Truncation 1 was caused by part of the intron after exon 8 being included in the cDNA and a novel 10 amino acids being added to the partial Sema2b polypeptide. Truncation 2 resulted from exon 4 splicing directly to exon 10 and skipping exons 5–9. Sixteen novel amino acids were added to the partial Sema2b polypeptide. Truncation 3 resulted from exon 6 splicing to the last 8 nucleotides of exon13 and skipping exons 7–12. This resulted in a partial Sema2b polypeptide with 19 additional amino acids.