Srp20-Human Alternative Splicing Factor: Difference between revisions

The SRp20 protein is an alternative splicing factor found in homo sapiens as well as many other [https://en.wikipedia.org/wiki/Eukaryote eukaryotes]. [[Image:AASequence.jpg|350px|right|thumb|'''Figure 3.''' SRp20 Domain Representation. Shown are the RRM (green), the TAP binding linker (red line) and SR-rich domain (blue).]] It is a relatively small protein with a length of 164 amino acids and a weight of about 19kDa. In fact, it is the smallest member of the SR protein family. The protein contains two domains: a serine-arginine rich (SR) domain and a RNA-recognition motif (RRM) although only a 3D image of the RRM structure is presented here <ref name="Corbo2013">PMID:23685143</ref>.  

The splicing mechanism for SRp20 follows the normal eukaryotic mechanism, in which five different [https://en.wikipedia.org/wiki/SnRNP small nuclear ribonucleoproteins] (snRNPs) bring the splice sites together in order to start the reaction (Figure 1). Specifically, SRp20 and other SR proteins interact with the RNA ligand at the [https://en.wikipedia.org/wiki/Exonic_splicing_enhancer exonic splicing enhancer sequence] at the beginning of the 3’ splice site adjacent to the intron being removed. SRp20 facilitates the interaction of the U2 snRNP with the RNA to continue the mechanism (Figure 2)<ref name="Shepard">PMID:19857271</ref>. [[Image:mechanism1.png|300px|left|thumb|'''Figure 1.''' Splicing mechanism for eukaryotes. Free 3’OH nucleophile of adenosine in intron attacks phosphorus of phosphate creating a ring structure intron known as a lariat. The free 2’OH in the 5’ splice site (red) acts as the nucleophile to attack the phosphate of the first nucleotide in the 3’ splice site (red) to release the [https://news.brown.edu/articles/2012/06/lariats lariat] intron. The products include the final modified RNA sequence and the lariat which will be recycled.]] [[Image:prettymechanism.png|260px|right|thumb|'''Figure 2.''' SRp20 works with [https://en.wikipedia.org/wiki/U2_spliceosomal_RNA U2] snRNP: Five snRNPs are needed in the eukaryotic splicing mechanism to facilitate the reaction. The U2 snRNP must attach to the 3’ splice site to bring together the 5’ and 3’ splice sites (red). SRp20 facilitates binding of U2 to the 3’ splice site by binding to the exonic splicing enhancer sequence (blue) in the RNA at the backbone. U2 must bind before the other snRNPs can bind to continue the mechanism.]]