EXPRESSION OF THE RAT PROTAMINE-2 GENE IS SUPPRESSED AT THE LEVEL OF TRANSCRIPTION AND TRANSLATION
EXPRESSION OF THE RAT PROTAMINE-2 GENE IS SUPPRESSED AT THE LEVEL OF TRANSCRIPTION AND TRANSLATION
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DOI：
10.1016/0014-4827(90)90290-q
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发表时间：
1990-05-01
影响因子：
3.7
通讯作者：
HECHT, NB
中科院分区：
文献类型：
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作者：
BUNICK, D;BALHORN, R;HECHT, NB
我们将大鼠鱼精蛋白2基因序列（rP 2）与小鼠鱼精蛋白2（mP2）基因序列进行了比较。该序列包括编码区的435个核苷酸，该编码区包括120个核苷酸的内含子，编码序列5“处的461个核苷酸和3”处的181个碱基。在小鼠中，鱼精蛋白2基因被大量转录和翻译。mP2蛋白最初作为前体合成，然后进行蛋白水解加工以产生成熟蛋白。相比之下，在大鼠中，鱼精蛋白2转录本的含量为小鼠中的2-5%，并且在精子中从未检测到成熟蛋白。虽然有92%的大鼠和小鼠的基因之间的核苷酸相似性和91%的预测的氨基酸序列的相似性，在体外径流转录测定中进行的大鼠或小鼠睾丸衍生的转录系统显示，rP 2启动子是只有30%的有效的启动子作为MP2启动子。从附睾精子中提取的总精子碱性核蛋白的分析表明，大鼠P2 mRNA在体内翻译，但没有得到适当的处理，使用特异性的鱼精蛋白2的单克隆抗体。这些结果表明，大鼠精蛋白2基因的转录速率降低和加工位点的改变可能有助于大鼠精子中精蛋白2的缺乏。
We have compared the rat protamine 2 gene sequence (rP2) to that of the mouse protamine 2 (mP2) gene. The sequence encompasses 435 nucleotides of the coding region which includes an intron of 120 nucleotides, 461 nucleotides 5'' to the coding sequence and 181 bases 3'' to it. In the mouse the protamine 2 gene is abundantly transcribed and translated. The mP2 protein is initially synthesized as a precursor and then proteolytically processed to yield the mature protein. In contrast, in the rat, protamine 2 transcripts are present at 2-5% that found in the mouse and the mature protein has never been detected in spermatozoa. Although there is 92% nucleotide similarity between rat and mouse genes and 91% similarity of the predicted amino acid sequences, in vitro runoff transcription assays performed in either rat or mouse testis-derived transcription systems reveal that the rP2 promoter is only 30% as efficient a promoter as the mP2 promoter. Analyses of total sperm basic nuclear proteins extracted from epididymal sperm using a monoclonal antibody specific for protamine 2 suggest that the rat P2 mRNA is translated in vivo but is not properly processed. These results suggest that the lowered transcription rate and altered processing sites of the rat protamine 2 gene are likely to contribute to the lack of protamine 2 in rat spermatozoa.