title: Dynamic association of proteins with the pre-mRNA branch region.
abstract: The association of proteins with the branch site region during pre-mRNA splicing was probed using a novel methodology to site-specifically modify the pre-mRNA with the photo-reagent benzophenone. Three sets of proteins were distinguished by the kinetics of their associations with pre-mRNAs, by their association with discrete splicing complexes, and by their differing factor requirements. An early U1 snRNP-dependent cross-link of the branch region to a p80 species was followed by cross-links to p14, p35, and p150 polypeptides associated with the U2 snRNP-pre-mRNA complex. Concomitant with formation of the spliceosome, a rearrangement of protein factors about the branch region occurred, in which the p35 and p150 cross-links were replaced by p220 and p70 species. These results establish that the branch region is recognized in a dynamic fashion by multiple distinct proteins during the course of spliceosomal assembly.
authors.affiliation: Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139-4307.
authors.forename: A M
authors.initials: AM
authors.lastname: MacMillan
authors.forename: C C
authors.initials: CC
authors.lastname: Query
authors.forename: C R
authors.initials: CR
authors.lastname: Allerson
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: G L
authors.initials: GL
authors.lastname: Verdine
authors.forename: P A
authors.initials: PA
authors.lastname: Sharp
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008961:Models, Structural; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D009843:Oligoribonucleotides; D012322:RNA Precursors / Q000737:chemistry* / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000737:chemistry* / Q000378:metabolism; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000737:chemistry / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000737:chemistry / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000378:metabolism*; D017381:Spliceosomes / Q000737:chemistry*
chemical_list: D009838:Oligodeoxyribonucleotides; D009843:Oligoribonucleotides; D012322:RNA Precursors; D012342:RNA, Small Nuclear; D017412:Ribonucleoprotein, U1 Small Nuclear; D017413:Ribonucleoprotein, U2 Small Nuclear; D012261:Ribonucleoproteins