Synthesis of β-tubulin occurs within chromatoid body of round spermatids.
Synthesis of β-tubulin occurs within chromatoid body of round spermatids.
复制标题
β-微管蛋白的合成发生在圆形精子细胞的类染色体内。
作者：
Fujii Y;Fujita H;Yokota S
在精子细胞中所需的蛋白质的mRNA被认为在早期转录并储存在细胞质中，可能储存在拟染色体体（CB）中，这是一种类型的营养成分（在精子发生过程中出现和消失的独特结构），因为基因的转录在晚期不发生。在细长精子细胞中，需要大量的微管蛋白分子来形成鞭毛和柄微管。为了研究CB在微管蛋白mRNA翻译中的可能作用，我们对大鼠生精细胞中的α和β微管蛋白进行了免疫荧光和免疫电镜定位研究。CB中检测到β-微管蛋白，但未检测到α-微管蛋白。粗线期精母细胞（ISPG、IMC、SB）中存在的其他营养成分对α-和β-微管蛋白均呈阴性。我们的研究结果表明：（i）圆形精子细胞中的β-微管蛋白在CB内翻译，而α-微管蛋白不在CB内翻译;（ii）αβ-异源二聚体在CB外形成，并掺入到柄和鞭毛的微管中。
mRNAs for proteins required in elongated spermatids are considered to be transcribed at an early stage and stored in cytoplasm, presumably in chromatoid body (CB), one type of nuage component (a unique structure that appears and disappears during spermatogenesis), because transcription of genes does not occur at late stages. In elongated spermatids, a large amount of tubulin molecules is required to form microtubules of manchette and flagellum. To investigate the possible role of CB in translation of tubulin mRNA, we performed immunofluorescence and immunoelectron microscopic localization studies of α‐ and β‐tubulin in rat spermatogenic cells. β‐tubulin was detected in CB, but α‐tubulin was not. Other nuage components present in pachytene spermatocytes (ISPG, IMC, SB) were negative for both α‐ and β‐tubulin. Our findings suggest that: (i) β‐tubulin in round spermatids is translated within the CB, whereas α‐tubulin is not; (ii) αβ‐heterodimers are formed outside CB and incorporated into microtubules of manchette and flagellum.