title: A testis cytoplasmic RNA-binding protein that has the properties of a translational repressor.
abstract: Translation of the mouse protamine 1 (Prm-1) mRNA is repressed for several days during male germ cell differentiation. With the hope of cloning genes that regulate the translational repression of Prm-1, we screened male germ cell cDNA expression libraries with the 3' untranslated region of the Prm-1 RNA. From this screen we obtained two independent clones that encode Prbp, a Prm-1 RNA-binding protein. Prbp contains two copies of a double-stranded-RNA-binding domain. In vitro, the protein binds to a portion of the Prm-1 3' untranslated region previously shown to be sufficient for translational repression in transgenic mice, as well as to poly(I). poly(C). Prbp protein is present in multiple forms in cytoplasmic extracts prepared from wild-type mouse testes and is absent from testes of germ cell-deficient mouse mutants, suggesting that Prbp is restricted to the germ cells of the testis. Immunocytochemical localization confirmed that Prbp is present in the cytoplasmic compartment of late-stage meiotic cells and haploid round spermatids. Recombinant Prbp protein inhibits the translation of multiple mRNAs in a wheat germ lysate, suggesting that Prbp acts to repress translation in round spermatids. While this protein lacks complete specificity for Prm-1-containing RNAs in vitro, the properties of Prbp are consistent with it acting as a general repressor of translation.
authors.affiliation: Department of Genetics, University of Washington, Seattle 98195, USA.
authors.forename: K
authors.initials: K
authors.lastname: Lee
authors.forename: M A
authors.initials: MA
authors.lastname: Fajardo
authors.forename: R E
authors.initials: RE
authors.lastname: Braun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011479:Protamines / Q000235:genetics; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology; D013737:Testis / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D018076:DNA, Complementary; C082073:PRM1 protein, human; C513176:Prm1 protein, mouse; D011479:Protamines; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins