Twenty-five years ago, we and others suggested that the types of introns found in fission yeast F. saccharomyces yeast represent a different type of introns found in Saccharomyces cerevisiae. This recommendation is mainly based on the observation that simian virus 40 (SV40) small T antigen transcripts showing 66 nt introns are accurately displayed, and small T antigen proteins are synthesized in Schizosaccharomyces pombe, but There is no synthesis. We used fission yeast and generated temperature-sensitive (ts) mutants to screen those mutants that indicate pre-mRNA splicing defects at limiting temperatures. For these screens, we constructed an artificial reporter gene using the natural intron-free ura4 gene encoding the carboxylase involved in uracil synthesis. Insertion of an intron into the ura4 gene led to the discovery that introns in Schizosaccharomyces pombe can be identified independently of its exon background. It was then shown that introns in Schizosaccharomyces pombe have been identified by a mechanism now called "intron definition". The ts mutant was transformed with a plasmid containing a 108 bp intron sequence in the ura4 gene. Then, compare the presence of mRNA and pre-mRNA of the ura4-108I transcript under the conditions of growth (permissible temperature of 25 ° C) and non-growth (restricted temperature of 36 ° C). Of the hundreds of ts mutants, three showed spliced (mRNA) and unspliced (pre-mRNA) transcripts of the ura4-I108 reporter gene at allowable temperatures, but the mRNA was time-dependent when transferred to a limiting temperature Sexual decline was observed while pre-mRNA remained stable. This indicates that the ura4-108I gene was still transcribed, but artificial introns were not removed under this condition. In addition, the natural introns of the cdc2 transcripts in these mutants were not removed at the limiting temperature.
Mammalian Prp4K has been shown to interact with many different cellular structures and defined proteins (e.g. spots, spliceosome particles, chromatin tissue complexes) and proteins on kinetocore and co-localize proteins at checkpoints of tissue spindle assembly.
Two protein kinases, fission yeast Prp4 kinase and chimeric mouse Prp4 kinase, consist of a mouse kinase domain that precedes the N-terminal Prp4 of Schizosaccharomyces pombe, and enrich them in vitro for arginine/serine RS domain phosphorylation. The mammalian protein ASF/SF2. This protein belongs to the SR superfamily of splicing factors. The SR protein consists of one or two N-terminal RNA-binding domains (RBDs) and a C-terminal arginine / serine-rich (RS) domain. Members of the SR protein superfamily in mammals are involved in constitutive splicing and are specific regulators of alternative splicing. They bind to their partners and combine splicing with transcription and RNA output. The general function of SR proteins is regulated by reversible phosphorylation. In fission yeast, two SR proteins have been identified. Srp1 contains an RBD at the N-terminus, followed by three serine elements, which we call RS1, RS2, and RS3, respectively, which contain various numbers of SR and SP dipeptides. Phosphorylated proteomic analysis of fission yeast revealed several phosphorylated serines in these three RS elements. Srp2 contains two N-terminal RBD and two SR and SP dipeptide display elements at the C-terminus, which we call SR1 and SR2. Again, phosphoprotein analysis detected phosphorylated serine in these elements. Extensive mutation analysis was performed on two elements (SR1 and SR2) by replacing serine with other amino acids and testing the effect of mutations in vivo. The results showed that when both serine in both elements were mutated, the GFP-Srp2 fusion protein Unable to enter the nucleus, but found in different points distributed in the cell.
