Miller R C, Planck S R, Magun B E
J Recept Res. 1983;3(4):529-39. doi: 10.3109/10799898309041857.
A photoaffinity derivative of highly purified 125I-labelled epidermal growth factor (125-I-EGF) has been synthesized. The heterobifunctional crosslinking reagent p-azidophenylglyoxal (PAPG) was bound to arginine residues in 125I-EGF. PAPG-125 I-EGF bound to EGF receptors on rat fibroblasts and human A431 epidermoid carcinoma cells in culture. An apparent decreased affinity of PAPG-125I-EGF for the EGF receptor is in accord with at least one arginine being at or near the EGF receptor binding site. The PAPG-125I-EGF:EGF receptor complexes on rat cells were internalized to the same extent as control EGF:receptor complexes. A431 cells treated with PAPG-125I-EGF were irradiated with ultraviolet light and the labelled proteins were analyzed by SDS-polyacrylamide gel electrophoresis. The 3 major labelled proteins had apparent molecular weights ranging from 75,000 to 200,000. Only the labelling of the 200,000-Mr protein was prevented by the addition of excess unlabelled EGF with the PAPG-125I-EGF. This molecular weight is in agreement with the reported size of the EGF receptor plus EGF. A protein with apparent molecular weight of 100,000 was labelled by 125I-EGF by an unknown mechanism which was dependent on the dose of UV light and blocked by the addition of excess unlabelled EGF.
已合成了高纯度的¹²⁵I标记表皮生长因子（¹²⁵I-EGF）的光亲和衍生物。异双功能交联剂对叠氮苯乙二醛（PAPG）与¹²⁵I-EGF中的精氨酸残基结合。PAPG-¹²⁵I-EGF与培养的大鼠成纤维细胞和人A431表皮样癌细胞上的EGF受体结合。PAPG-¹²⁵I-EGF对EGF受体的亲和力明显降低，这与至少一个精氨酸位于EGF受体结合位点处或其附近是一致的。大鼠细胞上的PAPG-¹²⁵I-EGF：EGF受体复合物内化程度与对照EGF：受体复合物相同。用PAPG-¹²⁵I-EGF处理的A431细胞用紫外光照射，并用SDS-聚丙烯酰胺凝胶电泳分析标记的蛋白质。3种主要的标记蛋白表观分子量在75,000至200,000之间。只有200,000-Mr蛋白的标记可通过在PAPG-¹²⁵I-EGF中加入过量未标记的EGF来阻止。该分子量与报道的EGF受体加EGF的大小一致。一种表观分子量为100,000的蛋白质通过未知机制被¹²⁵I-EGF标记，该机制依赖于紫外光剂量，并可被加入过量未标记的EGF所阻断。
