title: Testis-specific RT7 protein localizes to the sperm tail and associates with itself.
abstract: The RT7 gene recently cloned by us is expressed as an abundant RNA in round spermatids. In vitro transcription-translation showed that the RT7 gene encodes a protein of 26-27 kDa on SDS-polyacrylamide gels. Here we report the development of monoclonal antibodies (mAbs) raised against a peptide from the predicted N-terminal amphipathic alpha-helix of the rat RT7 protein. All mAbs recognize RT7 protein or N-terminal parts of it. To investigate RT7 in vivo, mAbs were used in immunofluorescence microscopy and confocal laser immunofluorescence microscopy. Several mAbs recognize RT7 protein in elongating spermatids: the observed staining pattern suggests a nonrandom localization in these cells. Two mAbs recognize the protein only in sperm tails. Using co-immunoprecipitation assays, we found that RT7 can form stable complexes with itself that are associated through a region located in the N-terminal half of RT7. Our results identify the RT7 protein as a major sperm tail component and suggest that it may be a structural component of sperm tail outer dense fibers (ODF).
authors.affiliation: Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
authors.forename: N A
authors.initials: NA
authors.lastname: Higgy
authors.forename: T
authors.initials: T
authors.lastname: Pastoor
authors.forename: C
authors.initials: C
authors.lastname: Renz
authors.forename: H A
authors.initials: HA
authors.lastname: Tarnasky
authors.forename: F A
authors.initials: FA
authors.lastname: Van der Hoorn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001483:Base Sequence; D005455:Fluorescent Antibody Technique; D012739:Gonadal Steroid Hormones; D006360:Heat-Shock Proteins; D007163:Immunosorbent Techniques; D008297:Male; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D012313:RNA / Q000737:chemistry; D051381:Rats; D013082:Sperm Tail / Q000737:chemistry*; D013087:Spermatids / Q000737:chemistry; D013737:Testis / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D012739:Gonadal Steroid Hormones; D006360:Heat-Shock Proteins; C490108:Odf1 protein, rat; D011506:Proteins; D012313:RNA