title: Characterization and subcellular localization of Tektin 3 in rat spermatozoa.
abstract: Mammalian sperm flagella have filament-forming Tektin proteins (Tektin 1-5) reported to be involved in the stability and structural complexity of flagella. Male mice null for Tektin3 produce spermatozoa with reduced forward progression and increased flagellar structural bending defects. The subcellular localization of Tektin3 (TEKT3) in spermatozoa, however, has not been clarified at the ultrastructural level. To elucidate the molecular localization of TEKT3 in flagella of rat spermatozoa, we performed extraction studies followed by immunoblot analysis, immunofluorescence microscopy, and immunogold electron microscopy. Extraction of sperm flagella from the cauda epididymis resulted in complete removal of axonemal tubulins, while TEKT3 was resistant to extraction with the same S-EDTA (1% SDS, 75 mM NaCl, 24 mM EDTA, pH 7.6) solution, suggesting that TEKT3 might be present in the peri-axonemal component and not directly associated with axonemal tubulins. Resistance to S-EDTA extraction might be due to disulfide bond formation during epididymal maturation since concentrations of DTT greater than 5 mM drastically promoted release of TEKT3 from flagella. Immunofluorescence microscopy and pre-embedding immunoelectron microscopy revealed that TEKT3 was predominantly associated with the surface of mitochondria and outer dense fibers in the middle piece. In addition, TEKT3 was found to be present at the equatorial segment region of the acrosome membrane in sperm heads. TEKT3 might not only work as a flagellar constituent required for flagellar stability and sperm motility but also may be involved in acrosome-related events, such as the acrosome reaction or sperm-egg fusion.
authors: Laboratory of Zoology, Graduate School of Agriculture, Kyushu University, Higashiku Hakozaki 6-10-1, Fukuoka 812-8581 Japan.
authors: Hiroe
authors: H
authors: Takiguchi
authors: Emi
authors: E
authors: Murayama
authors: Takane
authors: T
authors: Kaneko
authors: Hitoshi
authors: H
authors: Kurio
authors: Kiyotaka
authors: K
authors: Toshimori
authors: Hiroshi
authors: H
authors: Iida
mesh_terms: D000177:Acrosome / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D004229:Dithiothreitol; D004492:Edetic Acid; D005407:Flagella / Q000737:chemistry / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008868:Microtubule Proteins / Q000737:chemistry / Q000378:metabolism*; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D012967:Sodium Dodecyl Sulfate; D013077:Sperm Head / Q000737:chemistry / Q000378:metabolism; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D008868:Microtubule Proteins; C044103:tektins; D012967:Sodium Dodecyl Sulfate; D004492:Edetic Acid; D004229:Dithiothreitol