Jong S M, Wang L H
Rockefeller University, New York, New York 10021.
Oncogene Res. 1987 Jun;1(1):7-21.
We examined the topography of P68gag-ros on the plasma membrane of UR2-transformed chicken embryo fibroblasts. First, radioiodination of intact UR2-transformed cells resulted in the labelling of P68. Second, immunofluorescence experiments showed that anti-p19 antibody, but not an anti-ros serum, stained nonpermeablized UR2-transformed nonproducer cells. Furthermore, protease digestion of intact UR2-transformed cells removed the putative extracellular domain (the p19 portion in P68gag-ros), leaving peptide fragments (p48/p46) which conformed to the size of the ros-encoded sequence in P68. Greater than 60% of P68 molecules were accessible to protease digestion. Based on these results, we conclude that P68gag-ros is a transmembrane protein located primarily on the plasma membrane of UR2-transformed cells. The p19 portion is exposed extracellularly while the kinase domain of ros lies within the cell.
我们检测了P68gag-ros在UR2转化的鸡胚成纤维细胞质膜上的拓扑结构。首先，对完整的UR2转化细胞进行放射性碘化标记，结果显示P68被标记。其次，免疫荧光实验表明，抗p19抗体而非抗ros血清能够对未通透的UR2转化的非生产细胞进行染色。此外，对完整的UR2转化细胞进行蛋白酶消化，去除了假定的细胞外结构域（P68gag-ros中的p19部分），留下了符合P68中ros编码序列大小的肽片段（p48/p46）。超过60%的P68分子可被蛋白酶消化。基于这些结果，我们得出结论，P68gag-ros是一种跨膜蛋白，主要位于UR2转化细胞的质膜上。p19部分暴露于细胞外，而ros的激酶结构域位于细胞内。
