title: Proteins of demembraned mouse sperm heads. Characterization of a major sperm-unique component.
abstract: A 15-kilodalton protein has been identified as a major component of the residual protein fraction of mouse epididymal/vas spermatozoal heads, demembraned by treatment with Triton X-100 and sequentially extracted with 1 M NaCl/2-mercaptoethanol/DNase I. Two-dimensional electrophoresis of that protein before and after treatment with alkaline phosphatase indicated that it is present in epididymal/vas spermatozoa as a series of five differentially phosphorylated molecules with pI 6.0-7.0. Cyto-immunofluorescence with an affinity-purified antibody to the 15-kDa protein localized that protein to a circumscribed region of the demembraned mouse sperm head mediad from the dorsal margin. By radioimmunoassay, the 15-kDa protein was shown to be sperm-unique and species-specific. The antibody was nonreactive with homogenates of meiotic spermatogenic cells and round spermatids (stages 1-11) but was reactive with a non-phosphorylated 15.5-kDa protein of elongating spermatids (stages 12-16) and testicular spermatozoa. Following alkaline phosphatase treatment, the spermatozoal 15-kDa protein migrated to the position of the spermatidal 15.5-kDa protein on a sodium dodecyl sulfate gel. Thus, we conclude that the 15-kDa protein of mouse spermatozoa is synthesized during the elongation phase of spermiogenesis (stages 12-16) and is phosphorylated in the terminal period of that phase and/or after excursion of spermatozoa from the seminiferous tubules.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004822:Epididymis; D005455:Fluorescent Antibody Technique; D006168:Guinea Pigs; D007525:Isoelectric Focusing; D008297:Male; D051379:Mice; D008970:Molecular Weight; D011506:Proteins / Q000032:analysis*; D011817:Rabbits; D011863:Radioimmunoassay; D051381:Rats; D013045:Species Specificity; D013077:Sperm Head / Q000032:analysis*; D013087:Spermatids / Q000032:analysis; D013094:Spermatozoa / Q000032:analysis*; D014649:Vas Deferens
chemical_list: D000596:Amino Acids; D011506:Proteins; D000469:Alkaline Phosphatase