Evidence for functional differences between the two sites of rabbit transferrin: effects of serum and carbon dioxide.
Evidence for functional differences between the two sites of rabbit transferrin: effects of serum and carbon dioxide.
复制标题
兔转铁蛋白两个位点之间功能差异的证据：血清和二氧化碳的影响。
DOI：
10.1016/0167-4889(90)90052-f
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Aisen,P
中科院分区：
文献类型：
--
作者：
Zak,O;Aisen,P
最近开发了一种将尿素凝胶电泳与Western免疫印迹相结合的技术，用于评估兔转铁蛋白每个铁结合位点向兔网织红细胞输送铁的相对能力。根据实验条件，可以使这两个位点以相同或不同的速率释放铁。在汉克斯的平衡盐溶液中，在室内空气或5%二氧化碳的气氛中，发现在90分钟的孵卵后，蛋白质n端叶的酸不稳定位点比酸稳定位点向网状红细胞提供铁的效率高1.4倍和2.9倍。观察到铁从两个位点的顺序释放和同时释放，但顺序释放仅从n端开始。在含20%血清的Hanks培养基中，在5% CO2中培养时，同一部位也被证明是更好的铁供体，供体为2倍。只有在空气中20%的血清中，这两个位点被发现是网织红细胞的等量铁供应者。在所研究的病例中，5%二氧化碳的气氛使酸性不稳定位点向网织红细胞提供铁的有效性增加了2倍，而20%血清的存在增强了酸性稳定c端位点的供铁能力。因此，转铁蛋白网织红细胞相互作用对环境变量很敏感，这种敏感性可能有助于解释先前关于两个转铁蛋白位点相对供铁能力的研究中存在的明显差异。
A recently developed technique combining urea gel electrophoresis with Western immunoblotting has been modified for assessing the relative ability of each iron binding site of rabbit transferrin in delivering iron to rabbit reticulocytes. The two sites can be made to release iron at the same or differing rates, depending on the experimental conditions. In Hanks' balanced salts solution in an atmosphere of room air or 5% CO2, the acid-labile site in the N-terminal lobe of the protein was found to be 1.4- and 2.9-times more effective than its acid-stable counterpart in providing iron to reticulocytes after 90 min incubation. Both sequential and simultaneous release of iron from the two sites was observed, but sequential release was initiated only from the N-terminal site. The same site also proved to be a better iron donor by a factor of 2 when incubations were conducted in Hanks' medium enriched with 20% serum in 5% CO2. Only in 20% serum in air were the two sites found to be equivalent iron suppliers to reticulocytes. In the cases studied, an atmosphere of 5% CO2increased 2-fold the effectiveness of iron donation by the acid-labile site to reticulocytes, while the presence of 20% serum enhanced the iron-donating ability of the acid-stable C-terminal site. Thus, the transferrinreticulocyte interaction is sensitive to environmental variables, and such sensitivity may help account for apparent discrepancies in previous studies of the relative iron-donating abilities of the two sites of transferrin.