Core component of the centrosome throughout spermatogenesis. May participate in mitotic spindle assembly and the mechanics of morphogenesis through an interaction with microtubules, either directly or indirectly. Is a target of several homeotic genes. Monomer. Localized to the centrosomes through complete nuclear cycles in mitotic and meiotic cells. Redistributed into the cytoplasm in G2 phase cells. In post-meiotic stages, found associated with the basal body of the maturing spermatid. Developing visceral mesoderm of the midgut, the central and peripheral nervous system, and developing gonads. Isoform J: Expressed in ovaries, testis and embryos. Isoform A: Expressed in testis only. Expressed both maternally and zygotically.