SRp20 is one of the smallest members of Ser- and Arg-rich protein family with 150 amino acids in the protein. The RNA recognition motif (RRM)of SRp20 has a βαββαβ topology, with two α-helices packed against one side of the four-stranded . The β-sheet surface has a large hydrophobic core with the aromatic amino acids Tyr, Phe, and Trp. The aromatic amino acid residues in the β-sheet are what cause the affinity of RNA for SRp20. When RNA binds to to SRp20, 3-8 nucleotides in the RNA bind to the four-stranded β-sheet in the . TAP binds to the α-helices that are opposite the β-sheet in the RRM. So, RNA binds to one side of the RRM and TAP binds to the other.(1)
Function
SRp20 is important for alternative RNA splicing. SRp20 can work with the C-terminal domain (CTD) of RNA pol II to remove exons from RNA after transcription. A mechanism for this has not been proposed, however it is clear that the CTD and SRp20 must be present in order for alternative splicing of some exons to occur. (2)
Disease
Relevance
