title: Scp160p, a multiple KH-domain protein, is a component of mRNP complexes in yeast.
abstract: Scp160p is a 160 kDa protein in the yeast Saccharomyces cerevisiae that contains 14 repeats of the hnRNP K-homology (KH) domain, and demonstrates significant sequence homology to a family of proteins collectively known as vigilins. As a first step towards defining the function of Scp160p, we have characterized the subcellular distribution and in vivo interactions of this protein. Using sucrose gradient fractionation studies we have demonstrated that Scp160p in cytoplasmic lysates is predominantly associated with polyribosomes. Furthermore, we have found that Scp160p is released from polyribosomes by EDTA in the form of a large complex of> or =1300 kDa that is sensitive both to RNase and NaCl. Using affinity-chromatography to isolate these complexes, we have identified two protein components other than Scp160p: poly(A) binding protein, Pab1p, and Bfr1p. The presence of Pab1p confirms these complexes to be mRNPs. The presence of Bfr1p is intriguing because the null phenotype for this gene is essentially the same as that reported for scp160 -null cells: increased cell size and aberrant DNA content. These results demonstrate that Scp160p associates with polyribosome-bound mRNP complexes in vivo, implicating a role for this protein in one or more levels of mRNA metabolism in yeast.
authors.affiliation: Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University, Atlanta, GA, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Lang
authors.forename: J L
authors.initials: JL
authors.lastname: Fridovich-Keil
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004492:Edetic Acid; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005800:Genes, Fungal; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D039102:Poly(A)-Binding Proteins; D011132:Polyribosomes / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: C089100:BFR1 protein, S cerevisiae; D017931:DNA Primers; D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009687:Nuclear Proteins; D039102:Poly(A)-Binding Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; C097262:SCP160 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C026452:messenger ribonucleoprotein; D004492:Edetic Acid; D012260:Ribonucleases