Composition and stability of PRPF31 and its two variants. (A) Schematic diagram of human and zebrafish PRPF31 and two mutants which mimic human AD5 and SP117 variants. Position of NOSIC and NOP domains (for details see text) and predicted nuclear localization signal (NLS) are indicated. The zebrafish AD5 variant is a truncated version (382 aa) to mimic human AD5 which has a 11 bp deletion leading to a frameshift after amino acid 371 (corresponding to zebrafish aa 382; see Additional file 1, Figure S1). SP117 mutation: A 1 bp insertion at 801/802 (in human at 769/770) leads to a frameshift after aa 267 (in human after aa 256), leading to 21 missense aa. (B) Western blot assays showing protein levels of Prpf31, AD5 and SP117 mutant variants over 29 hpf after injection of 61 nM mRNAs, respectively. "con" refers to non-injected wild-type embryos. (C) Degradation curves of Prpf31, AD5 and SP117 proteins (analyzed by Image J).