Identification of mouse CPX-2, a novel member of the metallocarboxypeptidase gene family: cDNA cloning, mRNA distribution, and protein expression and characterization.
Identification of mouse CPX-2, a novel member of the metallocarboxypeptidase gene family: cDNA cloning, mRNA distribution, and protein expression and characterization.
复制标题
小鼠 CPX-2（金属羧肽酶基因家族的新成员）的鉴定：cDNA 克隆、mRNA 分布以及蛋白质表达和表征。
DOI：
10.1089/dna.1998.17.897
复制
发表时间：
1998
影响因子：
3.1
通讯作者：
Fricker,LD
中科院分区：
文献类型：
--
作者：
Xin,X;Day,R;Dong,W;Lei,Y;Fricker,LD
从其与羧肽酶E的同源性中鉴定出一个新的羧肽酶基因家族成员，命名为CPX-2。该cDNA全长2500个核苷酸，编码764个氨基酸，包含一个N端信号肽样序列、一个158个残基的盘状结构域和一个400个残基的羧肽酶结构域。400个残基的羧肽酶结构域与AEBP-1蛋白质具有59%的氨基酸同一性;与羧肽酶E、N和Z具有44%至46%的同一性;与羧肽酶基因家族的其他成员具有较低的同源性。CPX-2的盘状结构域与盘状蛋白-I的碳水化合物结合结构域具有22%的氨基酸同一性，与人因子V和VIII的磷脂结合结构域具有29%至34%的同一性，并且与AEBP-1上的盘状结构域具有59%的同一性。CPX-2缺失了几个预测的活性位点残基，这些残基在大多数羧肽酶基因家族的其他成员中是保守的，并且被认为是酶活性所必需的。使用杆状病毒系统表达CPX-2产生了几种形式的蛋白质，从80至105 kDa，但对各种羧肽酶底物没有检测到活性。一个较短的50 kDa形式的CPX-2，其中含有羧肽酶结构域，但不盘状结构域，也是无活性的杆状病毒系统中表达时。CPX-2能够与Sepharose-Arg结合;这种结合被10 mM Arg阻断。北方印迹分析显示CPX-2 mRNA在小鼠脑、肝、肾和肺中均有表达，原位杂交显示CPX-2 mRNA在脑中有广泛的分布。CPX-2富集的区域包括海马、大脑皮层、正中隆起和脉络丛。总之，这些数据表明CPX-2的广泛功能，可能是作为一种结合蛋白，而不是活性羧肽酶。
A novel member of the metallocarboxypeptidase gene family was identified from its homology with carboxypeptidase E and has been designated CPX-2. The cDNA of 2500 nucleotides encodes a protein of 764 amino acids that contains an N-terminal signal peptide-like sequence, a 158-residue discoidin domain, and a 400-residue carboxypeptidase domain. The 400-residue metallocarboxypeptidase domain has 59% amino acid identity with a protein designated AEBP-1; 44% to 46% identity with carboxypeptidases E, N, and Z; and lower homology with other members of the metallocarboxypeptidase gene family. The discoidin domain of CPX-2 has 22% amino acid identity with the carbohydrate-binding domain of discoideum-I, 29% to 34% identity with the phospholipid-binding domain of human factors V and VIII, and 59% identity with the discoidin-like domain on AEBP-1. CPX-2 is missing several of the predicted active-site residues that are conserved in most other members of the metallocarboxypeptidase gene family and which are thought to be required for enzyme activity. Expression of CPX-2 using the baculovirus system produced several forms of protein, from 80 to 105 kDa, but no detectable activity toward a variety of carboxypeptidase substrates. A shorter 50-kDa form of CPX-2, which contains the carboxypeptidase domain but not the discoidin domain, was also inactive when expressed in the baculovirus system. CPX-2 is able to bind to Sepharose-Arg; this binding is blocked by 10 mM Arg. Northern blot analysis showed CPX-2 mRNA in mouse brain, liver, kidney, and lung.In situhybridization analysis of brain revealed a broad distribution. Areas that are enriched in CPX-2 include the hippocampus, cerebral cortex, median eminence, and choroid plexus. Taken together, these data suggest a widespread function for CPX-2, possibly as a binding protein rather than an active carboxypeptidase.