Ledoux D, Mereau A, Pieri I, Barritault D, Courty J
University Paris XII, Laboratoire de Biotechnologie des Cellules Eucaryotes, Créteil, France.
Growth Factors. 1991;5(3):221-31. doi: 10.3109/08977199109000286.
We have previously shown that only adult brain contained a detectable amount of high affinity receptors for basic Fibroblast growth factor (bFGF) whereas adult liver, kidney, lung, intestine or stomach showed only low affinity binding sites. We now have studied and compared the distribution of the receptors for acidic Fibroblast growth factor (aFGF) with that of bFGF receptors in the same tissues. Membrane binding of 125I-aFGF was time dependent, reversible and displaced by an excess of unlabeled aFGF. Scatchard analyses of binding data obtained with all tissue membrane preparations revealed the presence of at least one class of low affinity/high capacity interaction sites characterized by apparent Kd values ranging from 3.9 to 6.9 x 10(-8) M. Interestingly and as for bFGF, high affinity receptors for aFGF could be detected only in adult brain membranes. Cross-linking and Scatchard analyses indicate that this family of interaction was characterized by four molecular species of 175, 125, 95 and 70 kDa and by an apparent Kd value of 1.8 x 10(-10) M. Moreover, cross-competition binding assay revealed that these brain high affinity receptors were common for both acidic and basic FGF. These results suggest that these growth factors may share identical functions mediated by the same receptors highly expressed in the brain. Using a cDNA probe for the Bek form of FGF receptors, we were able to show that all the tissues studied expressed this mRNA (4.5 kb transcript) but probably not in sufficient amounts to account for the number of high affinity receptors that we detected only in the brain.
我们之前已经表明，只有成年大脑含有可检测到的碱性成纤维细胞生长因子（bFGF）高亲和力受体，而成年肝脏、肾脏、肺、肠道或胃仅显示低亲和力结合位点。我们现在研究并比较了酸性成纤维细胞生长因子（aFGF）受体与bFGF受体在相同组织中的分布。125I-aFGF的膜结合是时间依赖性的、可逆的，并且可被过量的未标记aFGF取代。对所有组织膜制剂获得的结合数据进行Scatchard分析，结果显示存在至少一类低亲和力/高容量相互作用位点，其表观解离常数（Kd）值范围为3.9至6.9×10^(-8) M。有趣的是，与bFGF一样，aFGF的高亲和力受体仅在成年脑膜中可检测到。交联和Scatchard分析表明，这一相互作用家族的特征是有175、125、95和70 kDa的四种分子形式，表观Kd值为1.8×10^(-10) M。此外，交叉竞争结合试验表明，这些脑高亲和力受体对酸性和碱性FGF是共同的。这些结果表明，这些生长因子可能通过大脑中高表达的相同受体介导相同的功能。使用针对FGF受体Bek形式的cDNA探针，我们能够表明所有研究的组织都表达这种mRNA（4.5 kb转录本），但表达量可能不足以解释我们仅在大脑中检测到的高亲和力受体数量。
