title: A novel testis-specific 105-kDa protein related to the 90-kDa heat-shock protein.
abstract: Brain 90- and 100-kDa heat-shock proteins (HSP90 and HSP100) were purified and antibodies against them prepared. The two antibodies were very specific and did not cross-react with each other. In rat, immunoblotting with the anti-HSP90 antibody showed the most abundant presence of HSP90 in testis as well as brain, compared with lung, liver, spleen, kidney, cardiac muscle, ovarium and uterus. The anti-HSP90 antibody showed the presence of a new 105-kDa protein in rat testis. This novel 105-kDa protein was also detected in brain at a very low concentration but not in HeLa cells or other organs including the uterus and ovarium. The testis 105-kDa protein was purified from rat testis; although it was clearly separable from HSP90 by two-dimensional gel electrophoresis, Q-Sepharose and hydroxyapatite column chromatographies, the properties of this protein were very similar to HSP90. The similarity was higher than 60% on peptide mapping with trypsin digestion, the 105-kDa protein cross-reacted with anti-HSP90 antibody, both were bound similarly to heparin-Sepharose gel and both are located in the cytosol fraction. When the 105-kDa protein was fractionated by HPLC, a molecular mass of 195 kDa was calculated, indicating that it is composed of two identical subunits, similarly to HSP90. The 105-kDa protein did not react with the anti-HSP100 antibody. There was a slight similarity between the 105-kDa protein and HSP100 on the peptide mapping. HSP100 was present in the microsomal fraction as well as in the cytosol. It is concluded that the 105-kDa protein is a testis-specific and HSP90-related protein.
authors.affiliation: Department of Biochemistry, Akita University, School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Itoh
authors.forename: Y
authors.initials: Y
authors.lastname: Tashima
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D001923:Brain Chemistry; D002417:Cattle; D002850:Chromatography, Gel; D003429:Cross Reactions; D015180:Electrophoresis, Gel, Two-Dimensional; D006367:HeLa Cells / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000276:immunology / Q000302:isolation & purification*; D008297:Male; D008970:Molecular Weight; D009928:Organ Specificity; D010449:Peptide Mapping; D011506:Proteins / Q000276:immunology / Q000302:isolation & purification*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000737:chemistry*
chemical_list: D006360:Heat-Shock Proteins; D011506:Proteins