Young S P, Garner C
Department of Rheumatology, University of Birmingham, U.K.
Biochem J. 1990 Jan 15;265(2):587-91. doi: 10.1042/bj2650587.
Following suggestions that transferrin present in fetal-bovine serum, a common supplement used in tissue-culture media, may not bind well to human cells, we have isolated the protein and investigated its interaction with both human and bovine cells. Bovine transferrin bound to a human cell line, K562, at 4 degrees C with a kd of 590 nM, whereas human transferrin bound with a kd of 3.57 nM, a 165-fold difference. With a bovine cell line, NBL4, bovine transferrin bound with the higher affinity, kd 9.09 nM, whereas human transferrin bound with a kd of 41.7 nM, only a 5-fold difference. These values were reflected in an 8.6-fold difference in the rate of iron delivery by the two proteins to human cells, whereas delivery to bovine cells was the same. Nevertheless, the bovine transferrin was taken up by the human cells by a specific receptor-mediated process. Human cells cultured in bovine diferric transferrin at 40 micrograms/ml, the concentration expected in the presence of 10% fetal-bovine serum, failed to thrive, whereas cells cultured in the presence of human transferrin proliferated normally. These results suggest that growth of human cells in bovine serum could give rise to a cellular iron deficiency, which may in turn lead to the selection of clones of cells adapted for survival with less iron. This has important consequences for the use of such cells as models, since they may have aberrant iron-dependent pathways and perhaps other unknown alterations in cell function.
有建议指出，组织培养基中常用的补充剂胎牛血清中存在的转铁蛋白可能与人类细胞结合不佳，因此我们分离了该蛋白，并研究了它与人类和牛细胞的相互作用。牛转铁蛋白在4℃下与人类细胞系K562结合，解离常数（kd）为590 nM，而人类转铁蛋白的kd为3.57 nM，相差165倍。对于牛细胞系NBL4，牛转铁蛋白以更高的亲和力结合，kd为9.09 nM，而人类转铁蛋白的kd为41.7 nM，仅相差5倍。这些数值反映在两种蛋白向人类细胞输送铁的速率相差8.6倍，而向牛细胞输送铁的速率相同。然而，牛转铁蛋白通过特定的受体介导过程被人类细胞摄取。在40微克/毫升的牛双铁转铁蛋白中培养的人类细胞，即在存在10%胎牛血清时预期的浓度，无法茁壮成长，而在人类转铁蛋白存在下培养的细胞则正常增殖。这些结果表明，人类细胞在牛血清中生长可能导致细胞铁缺乏，这反过来可能导致选择适应于在较少铁的情况下存活的细胞克隆。这对于将此类细胞用作模型具有重要影响，因为它们可能具有异常的铁依赖途径以及细胞功能中其他未知的改变。
