Protein carboxyl methyltransferase activity specific for age-modified aspartyl residues in mouse testes and ovaries: evidence for translation during spermiogenesis.
Protein carboxyl methyltransferase activity specific for age-modified aspartyl residues in mouse testes and ovaries: evidence for translation during spermiogenesis.
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小鼠睾丸和卵巢中年龄修饰的天冬氨酰残基特异的蛋白质羧甲基转移酶活性：精子发生过程中翻译的证据。
DOI：
10.1002/mrd.1120220308
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Millette,CF
中科院分区：
文献类型：
--
作者：
O'Connor,CM;Germain,BJ;Guthrie,KM;Aswad,DW;Millette,CF
用从牛脑中纯化的蛋白羧甲基转移酶(PCMT)制备的抗血清，比较了睾丸和卵巢中该酶的水平，并研究了PCMT在精子发生过程中的浓度调节。PCMT专门修饰年龄受损的天冬氨酸残基，在成熟的小鼠睾丸中的浓度明显高于卵巢。然而，PCMT存在于生殖细胞缺陷的卵巢和睾丸的提取液中，浓度几乎相同。在正常睾丸中，PCMT的浓度在出生后的头4-5周内增加了几倍，与睾丸生殖细胞的出现和成熟相平行。免疫化学和酶标法检测纯化的生精细胞中PCMT的比活性表明，圆形精子细胞和残体中的PCMT水平分别是粗线期精母细胞的两倍和3.5倍。这一结果与生精细胞中PCMT的合成和/或稳定性增强以及PCMT在精子发生的单倍体部分持续翻译是一致的。生精细胞中相对较高的PCMT水平可能对伴随精子细胞凝聚的蛋白质的广泛代谢或翻译上不活跃的精子中受损蛋白质的修复具有重要意义。
An antiserum prepared against the purified protein carboxyl methltransferase (PCMT) from bovine brain has been used to compare testicular and ovarian levels of the enzyme and to study the regulation of PCMT concentrations during spermatogenesis. The PCMT, which specifically modifies age‐damaged aspartyl residues, is present at a significantly higher concentration in mature mouse testis than in ovary. However, the PCMT is present at nearly equal concentrations in extracts of germ cell‐deficient ovaries and testes obtained from mutantatrichosislatrichosismice. In normal testis, the concentration of the PCMT increases severalfold during the first 4–5 weeks after birth, paralleling the appearance and maturation of testicular germ cells. Both immunochemical and enzymatic measurements of PCMT specific activities in purified spermatogenic cell preparations indicate that PCMT levels are twofold and 3.5‐fold higher in round spermatids and residual bodies, respectively, than in pachytene spermatocytes. The results are consistent with the enhanced synthesis and/or stability of the PCMT in spermatogenic cells and with the continued translation of the PCMT during the haploid portion of spermatogenesis. The relatively high levels of PCMT in spermatogenic cells may be important for the extensive metabolism of proteins accompanying spermatid condensation or for the repair of damaged proteins in translationally inactive spermatozoa.