title: Leucine periodicity of U2 small nuclear ribonucleoprotein particle (snRNP) A' protein is implicated in snRNP assembly via protein-protein interactions.
abstract: Recombinant A' protein could be reconstituted into U2 small nuclear ribonucleoprotein particles (snRNPs) upon addition to HeLa cell extracts as determined by coimmunoprecipitation and particle density; however, direct binding to U2 RNA could not be demonstrated except in the presence of the U2 snRNP B" protein. Mutational analysis indicated that a central core region of A' was required for particle reconstitution. This region consists of five tandem repeats of approximately 24 amino acids each that exhibit a periodicity of leucine and asparagine residues that is distinct from the leucine zipper. Similar leucine-rich (Leu-Leu motif) repeats are characteristic of a diverse array of soluble and membrane-associated proteins from yeasts to humans but have not been reported previously to reside in nuclear proteins. Several of these proteins, including Toll, chaoptin, RNase/angiogenin inhibitors, lutropin-choriogonadotropin receptor, carboxypeptidase N, adenylyl cyclase, CD14, and human immunodeficiency virus type 1 Rev, may be involved in protein-protein interactions. Our findings suggest that in cell extracts the Leu-Leu motif of A' is required for reconstitution with U2 snRNPs and perhaps with other components involved in splicing through protein-protein interactions.
authors.affiliation: Department of Microbiology and Immunology, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: L D
authors.initials: LD
authors.lastname: Fresco
authors.forename: D S
authors.initials: DS
authors.lastname: Harper
authors.forename: J D
authors.initials: JD
authors.lastname: Keene
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000276:immunology; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D007930:Leucine; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D012342:RNA, Small Nuclear / Q000378:metabolism; D011994:Recombinant Proteins; D012261:Ribonucleoproteins / Q000737:chemistry / Q000648:ultrastructure*; D017411:Ribonucleoproteins, Small Nuclear; D013552:Swine; D055517:snRNP Core Proteins
chemical_list: D001324:Autoantigens; D046911:Macromolecular Substances; D012342:RNA, Small Nuclear; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D007930:Leucine