go_id,ontology,go_term,term_definition,evidence
GO:0000350,BP,"generation of catalytic spliceosome for second transesterification step","Conformational rearrangement of the spliceosomal complex containing the RNA products from the 1st step of splicing to form the catalytic site for the second step of splicing.",IBA
GO:0000386,MF,"second spliceosomal transesterification activity","Catalysis of the second transesterification reaction of spliceosomal mRNA splicing. Ligation of the two exons occurs via a transesterification reaction where the free 3'-hydroxyl group of the 5' exon is the nucleophile attacking the 3' splice site. Non-expressed sequences are now detached from the exons. In cis splicing, the intron is in a lariat structure.",IBA
GO:0005634,CC,nucleus,"A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.",IEA
GO:0005681,CC,"spliceosomal complex","Any of a series of ribonucleoprotein complexes that contain snRNA(s) and small nuclear ribonucleoproteins (snRNPs), and are formed sequentially during the spliceosomal splicing of one or more substrate RNAs, and which also contain the RNA substrate(s) from the initial target RNAs of splicing, the splicing intermediate RNA(s), to the final RNA products. During cis-splicing, the initial target RNA is a single, contiguous RNA transcript, whether mRNA, snoRNA, etc., and the released products are a spliced RNA and an excised intron, generally as a lariat structure. During trans-splicing, there are two initial substrate RNAs, the spliced leader RNA and a pre-mRNA.",IBA
GO:0005682,CC,"U5 snRNP","A ribonucleoprotein complex that contains small nuclear RNA U5.",IDA
GO:0006397,BP,"mRNA processing","Any process involved in the conversion of a primary mRNA transcript into one or more mature mRNA(s) prior to translation into polypeptide.",IEA
GO:0008380,BP,"RNA splicing","The process of removing sections of the primary RNA transcript to remove sequences not present in the mature form of the RNA and joining the remaining sections to form the mature form of the RNA.",IEA
GO:0016607,CC,"nuclear speck","A discrete extra-nucleolar subnuclear domain, 20-50 in number, in which splicing factors are seen to be localized by immunofluorescence microscopy.",IEA
GO:0046540,CC,"U4/U6 x U5 tri-snRNP complex","A ribonucleoprotein complex formed by the association of the U4/U6 and U5 small nuclear ribonucleoproteins.",IBA
GO:0071021,CC,"U2-type post-spliceosomal complex","A spliceosomal complex that is formed following the second splicing event and contains the spliced product, the excised intron, and three snRNPs, including U5.",IBA
GO:0071048,BP,"nuclear retention of unspliced pre-mRNA at the site of transcription","The process involved in retention of incorrectly or incompletely spliced pre-mRNA within the nucleus at the site of transcription.",IBA