FHL1, SLIMMER, and KyoT2 domain structure. A, fhl1 gene exon structure with alternative splicing indicated. It generates FHL1, SLIMMER, and KyoT2 mRNAs. B, protein structure of FHL1 and alternative splice isoforms. The SLIMMER bait used in yeast two-hybrid studies comprised C-terminal LIM domain 3 followed by the SLIMMER-specific region including the nuclear localization signals (NLS), nuclear export sequences (NES), and the RBP-J-binding domain.