4a8x
Structure of the core ASAP complexStructure of the core ASAP complex
Structural highlights
FunctionRNPS1_HUMAN Part of pre- and post-splicing multiprotein mRNP complexes. Auxiliary component of the splicing-dependent multiprotein exon junction complex (EJC) deposited at splice junction on mRNAs. The EJC is a dynamic structure consisting of core proteins and several peripheral nuclear and cytoplasmic associated factors that join the complex only transiently either during EJC assembly or during subsequent mRNA metabolism. Component of the ASAP and PSAP complexes which bind RNA in a sequence-independent manner and are proposed to be recruited to the EJC prior to or during the splicing process and to regulate specific excision of introns in specific transcription subsets. The ASAP complex can inhibit RNA processing during in vitro splicing reactions. The ASAP complex promotes apoptosis and is disassembled after induction of apoptosis. Enhances the formation of the ATP-dependent A complex of the spliceosome. Involved in both constitutive splicing and, in association with SRP54 and TRA2B/SFRS10, in distinctive modulation of alternative splicing in a substrate-dependent manner. Involved in the splicing modulation of BCL2L1/Bcl-X (and probably other apoptotic genes); specifically inhibits formation of proapoptotic isoforms such as Bcl-X(S); the activity is different from the established EJC assembly and function. Participates in mRNA 3'-end cleavage. Involved in UPF2-dependent nonsense-mediated decay (NMD) of mRNAs containing premature stop codons. Also mediates increase of mRNA abundance and translational efficiency. Binds spliced mRNA 20-25 nt upstream of exon-exon junctions.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedThe ASAP complex interacts with the exon-junction complex (EJC), a messenger ribonucleoprotein complex involved in post-transcriptional regulation. The three ASAP subunits (Acinus, RNPS1 and SAP18) have been individually implicated in transcriptional regulation, pre-mRNA splicing and mRNA quality control. To shed light on the basis for and consequences of ASAP's interaction with the EJC, we have determined the 1.9-A resolution structure of a eukaryotic ASAP core complex. The RNA-recognition motif of RNPS1 binds to a conserved motif of Acinus with a recognition mode similar to that observed in splicing U2AF proteins. The Acinus-RNPS1 platform recruits the ubiquitin-like domain of SAP18, forming a ternary complex that has both RNA- and protein-binding properties. Unexpectedly, our structural analysis identified an Acinus-like motif in Pinin, another EJC-associated splicing factor. We show that Pinin physically interacts with RNPS1 and SAP18, forming an alternative ternary complex, PSAP. The structure of the ASAP core complex reveals the existence of a Pinin-containing PSAP complex.,Murachelli AG, Ebert J, Basquin C, Le Hir H, Conti E Nat Struct Mol Biol. 2012 Mar 4;19(4):378-86. doi: 10.1038/nsmb.2242. PMID:22388736[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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