Composition and functional characterization of the yeast spliceosomal penta-snRNP.
Pre-mRNA introns are spliced in a macromolecular machine, the spliceosome. For each round of splicing, the spliceosome assembles de novo in a series of ATP-dependent steps involving numerous changes in RNA-RNA and RNA-protein interactions. As currently understood, spliceosome assembly proceeds by addition of discrete U1, U2, and U4/U6*U5 snRNPs to a pre-mRNA substrate to form functional splicing complexes. We characterized a 45S yeast penta-snRNP which contains all five spliceosomal snRNAs and over 60 pre-mRNA splicing factors. The particle is functional in extracts and, when supplied with soluble factors, is capable of splicing pre-mRNA. We propose that the spliceosomal snRNPs associate prior to binding of a pre-mRNA substrate rather than with pre-mRNA via stepwise addition of discrete snRNPs.
Stevens
Scott W
SW
California Institute of Technology, Division of Biology 147-75, Pasadena, CA 91125, USA.
Ryan
Daniel E
DE
Ge
Helen Y
HY
Moore
Roger E
RE
Young
Mary K
MK
Lee
Terry D
TD
Abelson
John
J
D014176:Protein Biosynthesis; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism*
D012322:RNA Precursors; D017411:Ribonucleoproteins, Small Nuclear