Isolation and characterization of CA XIV, a novel membrane-bound carbonic anhydrase from mouse kidney
Isolation and characterization of CA XIV, a novel membrane-bound carbonic anhydrase from mouse kidney
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DOI：
10.1074/jbc.274.22.15701
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发表时间：
1999-05-28
影响因子：
4.8
通讯作者：
Nakao, K
中科院分区：
文献类型：
--
作者：
Mori, K;Ogawa, Y;Nakao, K
碳酸酐酶（Carbonic anhydrase，CA）参与酸碱平衡、二氧化碳和离子的运输等多种生理过程。在本研究中，我们成功地分离了一个新的CA从小鼠肾脏中使用的信号序列陷阱的方法。它是一种337个氨基酸的多肽，计算分子量为37.5 kDa，由一个推定的氨基末端信号序列、一个CA结构域、一个跨膜结构域和一个短的亲水性羧基末端组成，我们将其命名为CA XIV。(1)CA XIV的CA结构域与已知CA的CA结构域高度同源，特别是细胞外CA，包括CA XII、IX、VI和IV。表位标记蛋白的表达研究表明CA XIV位于质膜上。当在COS-7细胞中表达时，CA XIV表现出主要与膜部分相关的CA活性。通过北方印迹分析，CA XIV的基因表达在肾脏和心脏中最丰富，其次是骨骼肌、脑、肺和肝脏。原位杂交显示，在肾脏中，该基因在近曲小管中强烈表达，近曲小管是碳酸氢盐重吸收的主要部分，也在外髓质的内条纹的外边缘。总之，我们已经克隆了一个功能性的cDNA编码一种新的膜结合CA。这项研究将为我们对二氧化碳代谢和酸碱平衡的理解带来新的见解。
Carbonic anhydrase (CA) is involved in various physiological processes such as acid-base balance and transport of carbon dioxide and ions. In this study, we have succeeded in the isolation of a novel CA from the mouse kidney by use of the signal sequence trap method. It is a 337-amino acid polypeptide with a calculated molecular mass of 37.5 kDa, consisting of a putative amino-terminal signal sequence, a CA domain, a transmembrane domain, and a short hydrophilic carboxyl terminus, which we designated CA XIV.(1) The CA domain of CA XIV is highly homologous with those of known CAs, especially extracellular CAs including CA XII, IX, VI, and IV. The expression study of an epitope-tagged protein has suggested that CA XIV is located on the plasma membrane. When expressed in COS-7 cells, CA XIV exhibits CA activity that is predominantly associated with the membrane fraction. By Northern blot analysis, the gene expression of CA XIV is most abundant in the kidney and heart, followed by the skeletal muscle, brain, lung, and liver. In situ hybridization has revealed that, in the kidney, the gene is expressed intensely in the proximal convoluted tubule, which is the major segment for bicarbonate reabsorption and also in the outer border of the inner stripe of the outer medulla. In conclusion, we have cloned a functional cDNA encoding a novel membrane-bound CA. This study will bring new insights into our understanding of carbon dioxide metabolism and acid-base balance.