Serine/arginine-rich splicing factor 2; Necessary for the splicing of pre-mRNA. It is required for formation of the earliest ATP-dependent splicing complex and interacts with spliceosomal components bound to both the 5’- and 3’-splice sites during spliceosome assembly. It also is required for ATP-dependent interactions of both U1 and U2 snRNPs with pre- mRNA. Interacts with other spliceosomal components, via the RS domains, to form a bridge between the 5’- and 3’-splice site binding components, U1 snRNP and U2AF. Binds to purine-rich RNA sequences, either 5’-AGSAGAGTA-3’ (S=C or G) or [...] (221 aa)

Serine/arginine-rich splicing factor 3; Splicing factor that specifically promotes exon- inclusion during alternative splicing. Interaction with YTHDC1, a RNA-binding protein that recognizes and binds N6-methyladenosine (m6A)-containing RNAs, promotes recruitment of SRSF3 to its mRNA-binding elements adjacent to m6A sites, leading to exon-inclusion during alternative splicing. Also functions as export adapter involved in mRNA nuclear export such as of histone H2A. Binds mRNA which is thought to be transferred to the NXF1-NXT1 heterodimer for export (TAP/NXF1 pathway); enhances NXF1-NXT [...] (164 aa)

Splicing factor 3A subunit 1; Subunit of the splicing factor SF3A required for ’A’ complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence (BPS) in pre-mRNA. Sequence independent binding of SF3A/SF3B complex upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the ’E’ complex; U2 small nucleolar ribonucleoprotein (793 aa)

Pre-mRNA-processing-splicing factor 8; Functions as a scaffold that mediates the ordered assembly of spliceosomal proteins and snRNAs. Required for the assembly of the U4/U6-U5 tri-snRNP complex. Functions as scaffold that positions spliceosomal U2, U5 and U6 snRNAs at splice sites on pre-mRNA substrates, so that splicing can occur. Interacts with both the 5’ and the 3’ splice site (2335 aa)

Splicing factor 3B subunit 1; Involved in pre-mRNA splicing as a component of the splicing factor SF3B complex. SF3B complex is required for ’A’ complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence (BPS) in pre-mRNA. Sequence independent binding of SF3A/SF3B complex upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the ’E’ complex. Belongs also to the minor U12-dependent spliceosome, which is involved in the splicing of rare class of nuclear pre-mRNA intron; Armadillo-like helical d [...] (1304 aa)

Protein BUD31 homolog; Spliceosomal Bact complex (144 aa)

Serine/arginine-rich splicing factor 1; Plays a role in preventing exon skipping, ensuring the accuracy of splicing and regulating alternative splicing. Interacts with other spliceosomal components, via the RS domains, to form a bridge between the 5’- and 3’-splice site binding components, U1 snRNP and U2AF. Can stimulate binding of U1 snRNP to a 5’-splice site-containing pre-mRNA. Binds to purine-rich RNA sequences, either the octamer, 5’-RGAAGAAC-3’ (r=A or G) or the decamers, AGGACAGAGC/AGGACGAAGC. Binds preferentially to the 5’- CGAGGCG-3’ motif in vitro. Three copies of the octame [...] (248 aa)

Splicing factor 1; Necessary for the ATP-dependent first step of spliceosome assembly. Binds to the intron branch point sequence (BPS) 5’-UACUAAC-3’ of the pre-mRNA. May act as transcription repressor; Spliceosomal A complex (673 aa)