Fig. 3

Kinase fusions identified in WT GIST samples. Three separate fusions involving the N-terminus of FGFR1 (a) and the C-terminus of NTRK3 (b) were identified. The FGFR1 fusions (a) were similar in structure to reported fusions and contained exons 2-17 fused with exons 5-22 of HOOK3 or exons 7-13 of TACC1. Intact coiled-coil motifs were present in both fusion partners and likely facilitate dimerization. Note that exon 1 of FGFR1 is non-coding and therefore excluded from the protein diagrams. The NTRK3 fusion (b) contained exons 1-5 of ETV6 and exons 14-19, which included the complete kinase domain. Although the portion of ETV6 present in the fusion lacked the DNA-binding domain, a Pointed (PNT) was conserved. This region is composed of 5-helix bundle involved in protein–protein interactions and may facilitate dimerization of this fusion. All diagrams are drawn to scale