The occurrence of two types of hemopexin-like protein in medaka and differences in their affinity to heme
The occurrence of two types of hemopexin-like protein in medaka and differences in their affinity to heme
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DOI：
10.1242/jeb.00897
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发表时间：
2004-03-01
影响因子：
2.8
通讯作者：
Watabe, S
中科院分区：
文献类型：
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作者：
Hirayama, M;Kobiyama, A;Watabe, S
从水稻HNI自交系中分离到编码mWap65-1和mWap65-2两种血凝素样蛋白的全长cDNA克隆。与mWap65-1相比，mWap65-2的氨基酸序列更接近于哺乳动物的血凝素。血红素与血红素高亲和力所需的组氨酸残基在mWap65-2中保守，而在mWap65-1中不保守。令人惊讶的是，mWap65-1，而不是mWap65-2，通过血红素-琼脂糖亲和层析显示出血红素结合能力，即使mWap65-1缺乏必需的组氨酸残基。此外，对不同组织的RT-PCR分析表明，mWap65-2的转录本仅限于肝脏，而mWap65-1的转录本则存在于肝脏、眼睛、心脏和大脑等多种组织中。定量RT-PCR结果显示，mWap65-2转录本在个体发育过程中比mWap65-1转录本表达早。然而，mWap65-1和mWap65-2的累积mRNA水平在10度和30度温度下驯化5周后均无显著差异。这些特征提示这两种蛋白具有不同的生理功能，mWap65-2不是血凝素。
Full-length cDNA clones encoding two types of hemopexin-like protein, mWap65-1 and mWap65-2, were isolated from the HNI inbred line of medaka Oryzias latipes. The deduced amino acid sequence of mWap65-2 resembled mammalian hemopexins more closely than that of mWap65-1. Histidine residues required for the high affinity of hemopexins for hemes were conserved in mWap65-2, but not in mWap65-1. Surprisingly, mWap65-1, but not mWap65-2, showed heme-binding ability as revealed by hemin-agarose affinity chromatography, even though mWap65-1 lacked the essential histidine residues. Furthermore, RT-PCR analysis of different tissues demonstrated that the transcripts of mWap65-2 were restricted to liver, whereas those of mWap65-1 were found in various tissues including liver, eye, heart and brain. Quantitative RT-PCR revealed that transcripts of mWap65-2 were expressed earlier than those of mWap65-1 during ontogeny. However, the accumulated mRNA levels of both mWap65-1 and mWap65-2 did not differ significantly in fish acclimated to either 10degreesC or 30degreesC for 5 weeks. These characteristics suggest that the two proteins have different physiological functions and that mWap65-2 is not a hemopexin.