AAR2/YBL074C Summary Help

Standard Name AAR2 1
Systematic Name YBL074C
Feature Type ORF, Verified
Description Component of the U5 snRNP complex; required for splicing of U3 precursors; originally described as a splicing factor specifically required for splicing pre-mRNA of the MATa1 cistron (1, 2 and see Summary Paragraph)
Name Description A1-Alpha2 Repression 1
Chromosomal Location
ChrII:87789 to 86722 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All AAR2 GO evidence and references
  View Computational GO annotations for AAR2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
Large-scale survey
reduction of function
42 total interaction(s) for 20 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 25
  • Affinity Capture-Western: 4
  • Biochemical Activity: 1
  • Co-crystal Structure: 2
  • Co-fractionation: 5
  • Co-localization: 1
  • Reconstituted Complex: 1

Genetic Interactions
  • Synthetic Lethality: 2
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 355
Molecular Weight (Da) 41,688
Isoelectric Point (pI) 4.77
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:87789 to 86722 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1068 87789..86722 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000170

AAR2 encodes a protein that is found as part of the U5 snRNP, either as part of a free U5 snRNP complex or as part of a U1/U5 snRNP complex. However, Aar2p is not found in other higher order complexes involving U5, either in the U4/U6.U5 tri-snRNP (composed of the U4/U6 and U5 snRNP complexes) or in the catalytically active spliceosome. When U5 associates with the U4/U6 complex to form the U4/U6.U5 tri-snRNP complex, Aar2p is released from the U5 snRNP. The role of Aar2p in mRNA splicing appears to be that of a recycling factor required to regenerate the form of the U5 snRNP that can associate with the U4/U6 snRNP complex to regenerate the U4/U6.U5 tri-snRNP . This tri-snRNP is recruited to the pre-mRNA by the U1 and U2 snRNPs to form the spliceosome.

Aar2p was originally characterized as a factor specifically required for the splicing of MATa1 pre-mRNA, but not for splicing of ACT1 pre-mRNA . The apparent specificity of the aar2 mutant defect in MATa1 pre-mRNA splicing seems to be due to a recycling defect exacerbated by the presence of two introns within the same gene, a rare occurrance in S. cerevisiae.

The free U5 snRNP complex is composed of Aar2p, Prp8p, Snu114p, and the seven Sm proteins that are common to the snRNPs for the U1, U2, U4, and U5 snRNAs . These Sm proteins and the genes encoding them are: SmB (SMB1), SmD1 (SMD1), SmD2 (SMD2), SmD3 (SMD3), SmE (SME1), SmF (SMX3), SmG (SMX2) .

Last updated: 2003-05-16 Contact SGD

References cited on this page View Complete Literature Guide for AAR2
1) Nakazawa N, et al.  (1991) AAR2, a gene for splicing pre-mRNA of the MATa1 cistron in cell type control of Saccharomyces cerevisiae. Mol Cell Biol 11(11):5693-700
2) Gottschalk A, et al.  (2001) The yeast U5 snRNP coisolated with the U1 snRNP has an unexpected protein composition and includes the splicing factor Aar2p. RNA 7(11):1554-65