title: Spnr, a murine RNA-binding protein that is localized to cytoplasmic microtubules.
abstract: Previous studies in transgenic mice have established the importance of the 3' untranslated region (UTR) of the spermatid-specific protamine-1 (Prm-1) mRNA in its translational control during male germ cell development. To clone genes that mediate the translational repression or activation of the Prm-1 mRNA, we screened cDNA expression libraries made with RNA from pachytene spermatocytes and round spermatids, with an RNA probe corresponding to the 3' UTR of Prm-1. We obtained six independent clones that encode Spnr, a spermatid perinuclear RNA-binding protein. Spnr is a 71-kD protein that contains two previously described RNA binding domains. The Spnr mRNA is expressed at high levels in the testis, ovary, and brain, and is present in multiple forms in those tissues. Immunolocalization of the Spnr protein within the testis shows that it is expressed exclusively in postmeiotic germ cells and that it is localized to the manchette, a spermatid-specific microtubular array. Although the Spnr protein is expressed too late to be directly involved in the translational repression of Prm-1 specifically, we suggest that the Spnr protein may be involved in other aspects of spermatid RNA metabolism, such as RNA transport or translational activation.
authors.affiliation: Department of Genetics, University of Washington, Seattle 98195, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Schumacher
authors.forename: K
authors.initials: K
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Edelhoff
authors.forename: R E
authors.initials: RE
authors.lastname: Braun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002451:Cell Compartmentation; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics; D005455:Fluorescent Antibody Technique; D015723:Gene Library; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008540:Meiosis / Q000502:physiology; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000302:isolation & purification*; D008870:Microtubules / Q000737:chemistry*; D008969:Molecular Sequence Data; D011479:Protamines / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D013090:Spermatocytes / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D013737:Testis / Q000737:chemistry; D014018:Tissue Distribution
chemical_list: D018076:DNA, Complementary; D008869:Microtubule-Associated Proteins; C513176:Prm1 protein, mouse; D011479:Protamines; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C093511:Strbp protein, mouse