On the diversity of secreted phospholipases A(2). Cloning, tissue distribution, and functional expression of two novel mouse group II enzymes.
On the diversity of secreted phospholipases A(2). Cloning, tissue distribution, and functional expression of two novel mouse group II enzymes.
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DOI：
10.1074/jbc.274.44.31195
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发表时间：
1999-10
期刊：
影响因子：
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通讯作者：
Emmanuel Valentin;F. Ghomashchi;Michael H. Gelb;M. Lazdunski;G. Lambeau
中科院分区：
文献类型：
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作者：
Emmanuel Valentin;F. Ghomashchi;Michael H. Gelb;M. Lazdunski;G. Lambeau
在过去的十年里，在哺乳动物中发现了越来越多的分泌型磷脂酶A(2)(Spla(2)S)。在这里，我们报告了另外三个Spla(2)S的克隆，它们被称为小鼠组IIE(MGIIE)、IIF(MGIIF)和X(MGX)Spla(2)S，从而在该物种中产生了八个不同的Spla(2)S。MGIIE和mGIIF Spla(2)S都含有典型的II组Spla(2)S的半胱氨酸，但与其他小鼠Spla(2)的同源性较低(不到51%)，表明这些酶是新的II组Spla(2)S。然而，mGIIF Spla(2)的一个独特特征是存在一个由23个氨基酸组成的单一半胱氨酸的C端延伸。MGX Spla(2)与之前克隆的人类X(HGX)Spla(2)有72%的同源性，并显示出相似的结构特征，因此MGX Spla(2)很可能是HGX Spla(2)的直系同源基因。MGIIE和mGIIF Spla(2)S位于4号染色体上，MGX Spla(2)位于16号染色体上。对22个组织进行的Northern和斑点杂交实验表明，所有8个小鼠Spla(2)S都有不同的组织分布，提示了各自特定的功能。MGIIE Spla(2)在子宫中高表达，在其他组织中低水平表达。MGIIF Spla(2)在胚胎发育和成体睾丸中表达较强。MGX Spla(2)主要在成人睾丸和胃中表达。将8种小鼠SplA(2)S的cDNA瞬时导入COS细胞，发现SplA(2)活性在细胞培养上清液中积累，表明每种酶都具有分泌和催化活性。以COS细胞为酶源，分析了新型SPLA2的pH速率谱和磷脂头基的特异性，并与其他小鼠SPLA2 S进行了比较。
Over the last decade, an expanding diversity of secreted phospholipases A(2) (sPLA(2)s) has been identified in mammals. Here, we report the cloning in mice of three additional sPLA(2)s called mouse group IIE (mGIIE), IIF (mGIIF), and X (mGX) sPLA(2)s, thus giving rise to eight distinct sPLA(2)s in this species. Both mGIIE and mGIIF sPLA(2)s contain the typical cysteines of group II sPLA(2)s, but have relatively low levels of identity (less than 51%) with other mouse sPLA(2)s, indicating that these enzymes are novel group II sPLA(2)s. However, a unique feature of mGIIF sPLA(2) is the presence of a C-terminal extension of 23 amino acids containing a single cysteine. mGX sPLA(2) has 72% identity with the previously cloned human group X (hGX) sPLA(2) and displays similar structural features, making it likely that mGX sPLA(2) is the ortholog of hGX sPLA(2). Genes for mGIIE and mGIIF sPLA(2)s are located on chromosome 4, and that of mGX sPLA(2) on chromosome 16. Northern and dot blot experiments with 22 tissues indicate that all eight mouse sPLA(2)s have different tissue distributions, suggesting specific functions for each. mGIIE sPLA(2) is highly expressed in uterus, and at lower levels in various other tissues. mGIIF sPLA(2) is strongly expressed during embryogenesis and in adult testis. mGX sPLA(2) is mostly expressed in adult testis and stomach. When the cDNAs for the eight mouse sPLA(2)s were transiently transfected in COS cells, sPLA(2) activity was found to accumulate in cell medium, indicating that each enzyme is secreted and catalytically active. Using COS cell medium as a source of enzymes, pH rate profile and phospholipid headgroup specificity of the novel sPLA(2)s were analyzed and compared with the other mouse sPLA(2)s.