Identification of a member of a new RNase a family specifically secreted by epididymal caput epithelium
Identification of a member of a new RNase a family specifically secreted by epididymal caput epithelium
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DOI：
10.1095/biolreprod.103.022459
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发表时间：
2004-02-01
影响因子：
3.6
通讯作者：
Dacheux, JL
中科院分区：
文献类型：
--
作者：
Castella, S;Fouchécourt, S;Dacheux, JL
本研究从猪附睾近头部位的体液中分离纯化了一种新的核糖核酸酶（RNase）A家族的第一个成员。这种蛋白质被命名为“Train A”，是公猪附睾前部分泌的最丰富的化合物。在2D电泳后，其特征在于超过10种异构体，大小从26至33 kDa，pi从5至8.5。对几种胰蛋白酶肽进行N-末端测序，并获得针对其中一种肽的抗血清。该蛋白免疫定位于附睾上皮近端头，特别是在高尔基带和顶端的主细胞的细胞质。在管腔中，精子为阴性，但在管腔内观察到反应产物液滴。TrainA cDNA全长序列是从一个猪附睾文库中获得的。该蛋白由213个氨基酸组成，包括一个23个氨基酸的肽信号和一个潜在的N-糖基化位点。这种蛋白质的mRNA已经在公牛、马和公羊中被检索和部分测序，并且在大鼠、小鼠和人类的数据库中发现了同源cDNA。所有序列在物种间高度保守。该蛋白及其mRNA是男性特异性的，并且仅在附睾的近端头表达，这是它们被发现的唯一位点。RNA酶A家族是一组具有或多或少的核糖核酸溶解活性的短蛋白（20-14 kDa），在体内具有不同的作用。然而，Train A蛋白存在一个长保守的N-末端特异性序列，并且不存在RNA酶催化位点，这表明Train A蛋白是一个新的RNA酶A家族的成员。
in this study, we purified the first member of a new ribonuclease (RNase) A family from fluid of the proximal caput of the boar epididymis. This protein, named "Train A," is the most abundant compound secreted in the anterior part of the boar epididymis. After 2D electrophoresis, it is characterized by more than 10 isoforms ranging in size from 26 to 33 kDa and pi from 5 to 8.5. Several tryptic peptides were N-terminal sequenced, and an antiserum against one of these peptides was obtained. The protein was immunolocalized in the epididymal epithelium of the proximal caput, especially in the Golgi zone and the apical cytoplasm of the principal cells. In the lumen, spermatozoa were negative but droplets of reaction product were observed within the lumen. Full lengths of Train A cDNA were obtained from a lambdagt11 boar caput epididymis library and sequenced. The deduced protein is composed of 213 amino acids, including a 23-amino acid peptide signal and a potential N-glycosylation site. The mRNA of this protein has been retrieved and partially sequenced in the bull, horse, and ram, and homologous cDNA is found in databanks for the rat, mouse, and human. All the sequences are highly conserved between species. This protein and its mRNA are male-specific and exclusively expressed in the proximal caput of the epididymis, the only site where they have been found. Train A presents an RNase A family motif in its sequence. The RNase A family is a group of several short proteins (20-14 kDa) with greater and lesser degrees of ribonucleolytic activity and with supposed different roles in vivo. However, the presence of a long-conserved N-terminal specific sequence and the absence of RNase catalytic site for Train A indicate that Train A protein is a member of a new family of RNase A.