Adolph Kenneth W
Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church St. S.E., Minneapolis, MN 55455, USA.
Gene. 2004 Apr 14;330:67-73. doi: 10.1016/j.gene.2004.01.005.
The metaxin genes of zebrafish have been investigated by determining the sequences of metaxin cDNAs and analyzing the translated amino acid sequences. A zebrafish cDNA corresponding to a third metaxin gene was identified. Zebrafish cDNAs representing metaxins 1 and 2, previously described in human and mouse, were also identified. The zebrafish metaxin genes are designated mtx1, mtx2 and mtx3, following zebrafish nomenclature guidelines. The zebrafish metaxin 3 (ZMTX3) cDNA codes for a protein of 313 amino acids (MW 35,208), while the ZMTX1 and ZMTX2 cDNAs specify proteins of 317 residues (MW 35,906) and 274 residues (MW 30,852), respectively. Alignment of the ZMTX3 and ZMTX1 amino acid sequences revealed 40% identities, while 26% identities were found for the ZMTX3/ZMTX2 alignment. A phylogenetic tree showed that the metaxins share a common ancestry, with the grouping of the zebrafish sequences with the homologous human and mouse sequences. Analysis of the domain structure of the zebrafish metaxins uncovered a glutathione S-transferase (GST) domain for each protein and, in addition, a thioredoxin-like domain for ZMTX2. A region of transmembrane helices was found near the C-terminus for the ZMTX1 protein. In addition, regions of alpha helix were seen to be the predominant feature of zebrafish metaxin secondary structure, particularly for ZMTX2 and ZMTX3. The ZMTX3 cDNA sequence has the greatest homology to a human sequence at cytogenetic location 5q14.1, close to the thrombospondin 4 gene (THBS4). Also, the mouse metaxin 3 homologue is adjacent to Thbs4 at 13C3.
通过测定metaxin cDNA序列并分析翻译后的氨基酸序列，对斑马鱼的metaxin基因进行了研究。鉴定出了与第三个metaxin基因对应的斑马鱼cDNA。还鉴定出了先前在人类和小鼠中描述过的代表metaxin 1和metaxin 2的斑马鱼cDNA。按照斑马鱼命名指南，将斑马鱼的metaxin基因命名为mtx1、mtx2和mtx3。斑马鱼metaxin 3（ZMTX3）cDNA编码一个由313个氨基酸组成的蛋白质（分子量35,208），而ZMTX1和ZMTX2 cDNA分别编码由317个残基（分子量35,906）和274个残基（分子量30,852）组成的蛋白质。ZMTX3和ZMTX-1氨基酸序列的比对显示有40%的一致性，而ZMTX3/ZMTX2比对的一致性为26%。系统发育树表明，metaxin有共同的祖先，斑马鱼序列与同源的人类和小鼠序列聚在一起。对斑马鱼metaxin结构域结构的分析发现，每种蛋白质都有一个谷胱甘肽S-转移酶（GST）结构域，此外，ZMTX2还有一个硫氧还蛋白样结构域。在ZMTX1蛋白的C末端附近发现了一个跨膜螺旋区域。此外，α螺旋区域是斑马鱼metaxin二级结构的主要特征，特别是对于ZMTX2和ZMTX3。ZMTX3 cDNA序列与细胞遗传学定位5q14.1处的人类序列具有最高的同源性，该位置靠近血小板反应蛋白4基因（THBS4）。同样，小鼠metaxin 3同源物在13C3处与Thbs4相邻。
