Functional association of U2 snRNP with the ATP-independent spliceosomal complex E.
In the current model for spliceosome assembly, U1 snRNP binds to the 5' splice site in the E complex followed by ATP-dependent binding of U2 snRNP to the branchpoint sequence (BPS) in the A complex. Here we report the characterization of highly purified, functional E complex. We provide evidence that this complex contains functional U2 snRNP and that this snRNP is required for E complex assembly. The BPS is not required for U2 snRNP binding in the E complex. These data suggest a model for spliceosome assembly in which U1 and U2 snRNPs first associate with the spliceosome in the E complex and then an ATP-dependent step results in highly stable U2 snRNP binding to the BPS in the A complex.
Das
R
R
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Zhou
Z
Z
Reed
R
R
D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D046911:Macromolecular Substances; D008961:Models, Structural; D009690:Nucleic Acid Conformation; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism*
D046911:Macromolecular Substances; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D017413:Ribonucleoprotein, U2 Small Nuclear; C088049:splicing factor 3a; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C112199:DHX38 protein, human; D053487:DEAD-box RNA Helicases