POINT MUTATION AT THE ATP BINDING-SITE OF EGF RECEPTOR ABOLISHES PROTEIN-TYROSINE KINASE-ACTIVITY AND ALTERS CELLULAR ROUTING
POINT MUTATION AT THE ATP BINDING-SITE OF EGF RECEPTOR ABOLISHES PROTEIN-TYROSINE KINASE-ACTIVITY AND ALTERS CELLULAR ROUTING
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DOI：
10.1016/0092-8674(87)90147-4
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发表时间：
1987-10-23
期刊：
影响因子：
64.5
通讯作者：
SCHLESSINGER, J
中科院分区：
文献类型：
--
作者：
HONEGGER, AM;DULL, TJ;SCHLESSINGER, J
用编码人EGF受体或EGF受体突变体的cDNA构建体转染缺乏内源性EGF受体的培养NIH 3T3细胞，其中ATP结合位点中的关键残基Lys721被丙氨酸残基取代。突变体受体被适当地处理，并且它显示出高亲和力和低亲和力的表面结合位点。与野生型受体不同，突变型受体不具有内在的蛋白酪氨酸激酶活性。野生型和突变型EGF受体的EGF内化初始速率相似。令人惊讶的是，突变受体没有下调，但似乎在转染细胞中回收。这些数据表明，正常EGF受体的降解后，内吞作用是由于内源性激酶活性，这种受体。单个氨基酸取代使得“下调的”受体变成可以从细胞质区室再循环回到细胞表面的受体。
Cultured NIH 3T3 cells devoid of endogenous EGF receptors were transfected with cDNA constructs encoding either the human EGF receptor or an EGF receptor mutant in which Lys721, a key residue in the ATP binding site, was replaced with an alanine residue. The mutant receptor was properly processed, and it displayed both high- and low-affinity surface binding sites. Unlike the wild-type receptor, the mutant receptor did not possess intrinsic protein-tyrosine kinase activity. The initial rate of EGF internalization was similar for wild-type and mutant EGF receptors. Surprisingly, the mutant receptors were not down regulated, but appeared to recycle in transfected cells. These data suggest that degradation of normal EGF receptors after endocytosis is due to the kinase activity endogenous to this receptor. A single amino acid substitution rendered a "down-regulated" receptor into a receptor that can recycle from cytoplasmic compartment back to the cell surface.