RESUMO
An extensive analysis of testis-expressed genes in the ascidian Ciona intestinalis explored a large number of genes of unknown function. Here we characterized these genes or gene products in a multidimensional manner. We analyzed genes both highly and uniquely expressed in the testis, as expected from the EST analysis. Immunolocalization of these proteins revealed that they are all expressed in sperm. Sperm membrane/matrix proteins play essential roles in cell responses and intracellular signaling at fertilization. By immunoscreening with antisera against the detergent-soluble and membrane fractions of sperm, we isolated 49 potential cDNA clones for membrane/matrix proteins. These included several unidentified genes, including a protein with sequence similarity to mammalian testicular cancer antigen Sp17. These data should facilitate exploration of the functions of uncharacterized sperm proteins and ultimately elucidate new molecular mechanisms in sperm physiology.
Assuntos
Etiquetas de Sequências Expressas/metabolismo , Regulação da Expressão Gênica/fisiologia , Testículo/metabolismo , Animais , Ciona intestinalis , Perfilação da Expressão Gênica , Imuno-Histoquímica , Masculino , Microdomínios da Membrana , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Transporte Proteico , EspermatozoidesRESUMO
We previously identified a 66 kDa axonemal protein (Ci-Axp66.0) in sperm of the ascidian Ciona intestinalis. Here we found that Ci-Axp66.0 shows sequence similarity to the DC2 subunit of the Chlamydomonas outer arm docking complex. Analysis of secondary structure of Ci-Axp66.0 suggested that the N-terminal two-thirds of the molecule is rich in coiled coil structure, as in Chlamydomonas DC2. Immunogold localization revealed that it is located in the vicinity of outer arm dynein. Ci-Axp66.0 was partly extracted from the axonemes by a high salt solution and co-purified with outer arm dynein. This co-purification was not affected by the absence of Mg(2+) in isolation buffer, indicating that Ci-Axp66.0 is associated with outer arm dynein. These results suggest that Ci-Axp66.0 is a component of the outer arm dynein docking complex in the axonemes of Ciona sperm.