MOLECULAR MECHANISM OF MITOGEN ACTION - PROCESSING OF RECEPTOR INDUCED BY EPIDERMAL GROWTH-FACTOR
MOLECULAR MECHANISM OF MITOGEN ACTION - PROCESSING OF RECEPTOR INDUCED BY EPIDERMAL GROWTH-FACTOR
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DOI：
10.1073/pnas.75.6.2644
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发表时间：
1978-01-01
影响因子：
11.1
通讯作者：
FOX, CF
中科院分区：
文献类型：
--
作者：
DAS, M;FOX, CF
利用亲和标记技术鉴定表皮生长因子（EGF）的膜受体，研究EGF结合后受体的生理命运。亲和标记细胞[Swiss小鼠3 T3]在37 ℃温育。C导致EGF-受体共价复合物放射性的时间依赖性损失（Mr 190，000）。在37 ℃孵育1小时期间，Mr 190，000条带的放射性损失（90%）。出现在62，000、47，000和37，000三个波段。完整细胞上的交联EGF-受体复合物（Mr 190，000）在4 ℃下可接近胰蛋白酶的作用。并与质膜部分共分馏。受体的蛋白水解产物不能被胰蛋白酶消化，在亚细胞分级分离中与溶酶体组分结合。放射性标记受体的内化和蛋白水解加工速率与EGF诱导的结合活性降低速率相同。EGF诱导的受体内化和加工之间的关系的研究，并刺激DNA合成，表明这两个过程是半最大刺激约0.1纳米EGF，浓度只有10%的受体位点被占用。在EGF半饱和的结合，但最佳的生物活性的浓度，有一个缓慢的，连续的受体内化和降解的过程，这可能是限制EGF诱导的有丝分裂。
An affinity labeling technique used previously for identification of a membrane receptor for epidermal growth factor (EGF) was exploited to investigate the physiological fate of receptor after binding of EGF. Incubation of affinity-labeled cells [Swiss mouse 3T3] at 37.degree. C resulted in a time-dependent loss of radioactivity from the EGF-receptor covalent complex (Mr 190,000). Radioactivity lost (90%) from the band of Mr 190,000 during a 1 h incubation at 37.degree. appeared in 3 bands of Mr 62,000, 47,000 and 37,000. The crosslinked EGF-receptor complex (Mr 190,000) on intact cells was accessible to the action of trypsin at 4.degree. and cofractionated with the plasmalemmal fraction. The proteolytic processing products of receptor were inaccessible to trypsin and banded with the lysosomal fraction on subcellular fractionation. The rate of internalization and proteolytic processing of radiolabeled receptor was the same as the rate of reduction of binding activity induced by EGF. A study of the relationship between EGF-induced receptor internalization and processing, and stimulation of DNA synthesis, showed that both these processes were half-maximally stimulated at approximately 0.1 nM EGF, a concentration at which only 10% of the receptor sites are occupied. At concentrations of EGF subsaturating for binding but optimal for biological activity, there is a slow, continuous process of receptor internalization and degradation which could be limiting for EGF-induced mitogenesis.