Magic™ Anti-splicing factor 1 (N-termianl)(phospho S82) polyclonal antibody

RNA SPLICING FACTOR1 (SF1) is responsible for recognizing the branch point site (BPS) sequence in introns and is critical for pre-mRNA splicing. In Arabidopsis (Arabidopsis thaliana), splicing factor1 (AtSF1) has been shown to retain the conserved function, but it is unexpected that null atsf1 mutants are viable. Here, we identified an allele of atsf1, named suppressor of thf1-4 (sot4), from suppressor screening for leaf variegation of thylakoid formation1. The sot4 mutant resulting from the G-to-R mutation at the highly conserved 198th amino acid residue within the functionally unknown domain exhibits leaf virescence associated with less accumulation of mature plastid ribosomal RNA, particularly under cold stress. Interestingly, the same point mutation in yeast Saccharomyces cerevisiae MUD synthetic-lethal 5p (SF1/Msl5p) also causes hypersensitivity to coldness and a low splicing activity for the introns with suboptimal BPS sequences. Transcriptomic profiling and reverse-transcription quantitative PCR analyses showed that expression of many genes were up- or downregulated in atsf1 via insufficient intron splicing. Our search for a BPS consensus from the retained introns in atsf1 transcriptomes, combined with RNA electrophoresis mobility shift assays, revealed that AtSF1 directly binds to the BPS consensus containing 5 '-CU(U/A)AU-3 '. Taken together, our data provide insight into a role for AtSF1 in regulating intron splicing efficiency, which helps plants acclimate to coldness.

In trypanosomes, mRNAs are processed by trans-splicing; in this process, a common exon, the spliced leader, is added to all mRNAs from a small RNA donor, the spliced leader RNA (SL RNA). However, little is known regarding how this process is regulated. In this study, we investigated the function of two serine-arginine-rich proteins, TSR1 and TSR1IP, implicated in trans-splicing in Trypanosoma brucei. Depletion of these factors by RNAi suggested their role in both cis- and trans-splicing. Microarray was used to examine the transcriptome of the silenced cells. The level of hundreds of mRNAs was changed, suggesting that these proteins have a role in regulating only a subset of T. brucei mRNAs. Mass-spectrometry analyses of complexes associated with these proteins suggest that these factors function in mRNA stability, translation, and rRNA processing. We further demonstrate changes in the stability of mRNA as a result of depletion of the two TSR proteins. In addition, rRNA defects were observed under the depletion of U2AF35, TSR1, and TSR1IP, but not SF1, suggesting involvement of SR proteins in rRNA processing.