RNA Binding Motif Protein 17 (RBM17)

Approximately half of the components excised from a 2-dimensional gel separation of the spliceosome were found in protein sequence databases. Using nanoelectrospray mass spectrometry, the remainder were identified and cloned using EST databases. One of the proteins characterized was a 45-kD splicing factor that the authors termed SPF45.The authors stated that SPF45 represents a novel class of second-step factors, and its interaction with Sxl was found to block splicing at the second step. These results were in contrast with other mechanisms of splicing regulation, which target early events of spliceosome assembly. A similar role for SPF45 was demonstrated in the activation of a cryptic 3-prime splice site generated by a common mutation in the HBB gene that causes beta-thalassemia.