FIGURE 1. Structure of known and identification of novel PDYN transcripts and proteins.

A. Previously described PDYN transcripts coding for the full-length (FL) and truncated proteins. The dominant FL1-PDYN and transcripts identified using RNA-Seq that differ in the length of the first exon and the presence of the second exon (GTEx 1–3), as well as three transcripts with alternative TSS, FL2 and testis-specific Taf I and Taf II transcripts, encode FL-PDYN protein. Other PDYN isoforms such as alternatively spliced Sp1 and Sp2 and transcripts initiated within the coding part of exon 4 (T1 and T2) may produce truncated PDYN proteins. Curved arrows show position of the translation initiation (TI).

B. Scheme of novel transcript identification. Human brain RACE-Ready cDNA was amplified in three rounds of nested PCR followed by digestion with BglII to eliminate the dominant FL-PDYN transcripts. The procedure allowed amplification of minor PDYN mRNA isoforms which then were analyzed by sequencing.

C. Structure of PDYN mRNAs consisting of four exons (boxes) and three introns (lines), and the localization of the primers used in the nested PCR are shown, not to scale. F and R depict forward and reverse primers (not to scale). αNE, DA and DB are the α-neoendorphin, dynorphin A and dynorphin B encoding sequences.

D, E. FL-PDYN and alternatively spliced ΔSP- and ΔSP/NLS-PDYN mRNA isoforms (D), and corresponding protein products (E). 3´-fragment of exon 1, exon 2 and 5´-fragment of exon 3 are spliced out in ΔSP- and ΔSP/NLS-transcripts. Two new introns are present in ΔSP/NLS mRNA isoform in exon 4 region; one of them overlaps with the dynorphin encoding domain, while another is located in the 3´-UTR (D). Signal peptide is truncated in both ΔSP- and ΔSP/NLS-PDYN. Putative NLS sequence is located in the dynorphin domain in FL- and ΔSP-PDYN but is absent in ΔSP/NLS-PDYN (E).