Fig. 2.

A single Platynereis Tcf gene produces multiple isoforms. a Known exon structure of Pdu-Tcf C terminus; N-terminal β-catenin binding domain is composed of at least 3 exons; two alternative exons for the beginning of HMG DNA binding domain, a common exon for most of the HMG domain, a premature stop codon within the intron following the HMG exon, alternative splice sites within a single C-clamp (CRARF) exon and a common C-terminal exon. Position of primers used to isolate the individual Pdu-Tcf isoforms is indicated. b The result of PCR on the cDNA template with the primers indicated in (a). Arrows point at three bands corresponding to three different splice variants amplified in each PCR. c Graphic representation of identified Pdu-Tcf isoforms in relation to their C-termini. We did not isolate the isoform X8, and we saw the isoform X6 only as a PCR product on gel. Note that these are isoforms which are defined only according to their C-termini and do not show the potential diversity of exons and alternative splicing in between the N-terminal β-catenin binding domain-encoding exon and C-terminal exons. Thus, each isoform listed here can actually form two or more variants