De Zoysa Mahanama, Lee Jehee
Department of Marine Biotechnology, College of Ocean Science, Cheju National University, 66 Jejudaehakno, Ara-dong, Jeju 690-756, Republic of Korea.
Fish Shellfish Immunol. 2007 Sep;23(3):624-35. doi: 10.1016/j.fsi.2007.01.013. Epub 2007 Jan 23.
Ferritin plays a key role in cellular iron metabolism, which includes iron storage and detoxification. From disk abalone, Haliotis discus discus, the cDNA that encodes the two ferritin subunits abalone ferritin subunit 1 (Abf1) and abalone ferritin subunit 2 (Abf2) were cloned. The complete cDNA coding sequences for Abf1 and Abf2 contained 621 and 549 bp, encoding for 207 and 183 amino acid residues, respectively. The H. discus discus Abf2 subunit contained a highly conserved motif for the ferroxidase center, which consists of seven residues of a typical vertebrate heavy-chain ferritin with a typical stem-loop structure. Abf2 mRNA contains a 27 bp iron-responsive element (IRE) in the 5'UTR position. This IRE exhibited 96% similarity with pearl and Pacific oyster and 67% similarity with human H type IREs. However, the Abf1 subunit had neither ferroxidase center residues nor the IRE motif sequence; instead, it contained iron-binding region signature 2 (IBRS) residues. Recombinant Abf1 and Abf2 proteins were purified and the respective sizes were about 24 and 21 kDa. Abf1 and Abf2 exhibited iron-chelating activity 44.2% and 22.0%, respectively, at protein concentration of 6 microg/ml. Analysis of tissue-specific expression by RT-PCR revealed that Abf1 and Abf2 ferritin mRNAs were expressed in various abalone tissues, such as gill, mantle, gonad, foot and digestive tract in a wide distribution profile, but Abf2 expression was more prominent than Abf1.
铁蛋白在细胞铁代谢中起关键作用，细胞铁代谢包括铁储存和解毒。从盘鲍（Haliotis discus discus）中克隆出了编码两种铁蛋白亚基的cDNA，即鲍鱼铁蛋白亚基1（Abf1）和鲍鱼铁蛋白亚基2（Abf2）。Abf1和Abf2的完整cDNA编码序列分别包含621和549个碱基对，分别编码207和183个氨基酸残基。盘鲍Abf2亚基包含一个高度保守的亚铁氧化酶中心基序，该基序由具有典型茎环结构的典型脊椎动物重链铁蛋白的七个残基组成。Abf2 mRNA在5'UTR位置含有一个27个碱基对的铁反应元件（IRE）。该IRE与珍珠和太平洋牡蛎的相似性为96%，与人类H型IRE的相似性为67%。然而，Abf1亚基既没有亚铁氧化酶中心残基也没有IRE基序序列；相反，它包含铁结合区域特征2（IBRS）残基。重组Abf1和Abf2蛋白被纯化，各自的大小约为24和21 kDa。在蛋白质浓度为6微克/毫升时，Abf1和Abf2分别表现出44.2%和22.0%的铁螯合活性。通过RT-PCR分析组织特异性表达发现，Abf1和Abf2铁蛋白mRNA在各种鲍鱼组织中表达，如鳃、外套膜、性腺、足和消化道，分布广泛，但Abf2的表达比Abf1更突出。
