ErbB3（HER3）受体蛋白的蛋白酪氨酸激酶同源结构域的生化特性
Biochemical characterization of the protein tyrosine kinase homology domain of the ErbB3 (HER3) receptor protein.
作者信息
Sierke S L, Cheng K, Kim H H, Koland J G
机构信息
Department of Pharmacology, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
出版信息
Biochem J. 1997 Mar 15;322 ( Pt 3)(Pt 3):757-63. doi: 10.1042/bj3220757.
The putative protein tyrosine kinase domain (TKD) of the ErbB3 (HER3) receptor protein was generated as a histidine-tagged recombinant protein (hisTKD-B3) and characterized enzymologically. CD spectroscopy indicated that the hisTKD-B3 protein assumed a native conformation with a secondary structure similar to that of the epidermal growth factor (EGF) receptor TKD. However, when compared with the EGF receptor-derived protein, hisTKD-B3 exhibited negligible intrinsic protein tyrosine kinase activity. Immune complex kinase assays of full-length ErbB3 proteins also yielded no evidence of catalytic activity. A fluorescence assay previously used to characterize the nucleotide-binding properties of the EGF receptor indicated that the ErbB3 protein was unable to bind nucleotide. The hisTKD-B3 protein was subsequently found to be an excellent substrate for the EGF receptor protein tyrosine kinase, which suggested that in vivo phosphorylation of ErbB3 in response to EGF could be attributed to a direct cross-phosphorylation by the EGF receptor protein tyrosine kinase.
ErbB3（HER3）受体蛋白的假定蛋白酪氨酸激酶结构域（TKD）作为组氨酸标签重组蛋白（hisTKD-B3）产生，并进行了酶学表征。圆二色光谱表明，hisTKD-B3蛋白呈现出与表皮生长因子（EGF）受体TKD二级结构相似的天然构象。然而，与源自EGF受体的蛋白相比，hisTKD-B3表现出可忽略不计的内在蛋白酪氨酸激酶活性。全长ErbB3蛋白的免疫复合物激酶测定也未产生催化活性的证据。先前用于表征EGF受体核苷酸结合特性的荧光测定表明，ErbB3蛋白无法结合核苷酸。随后发现hisTKD-B3蛋白是EGF受体蛋白酪氨酸激酶的优良底物，这表明体内ErbB3对EGF的磷酸化可能归因于EGF受体蛋白酪氨酸激酶的直接交叉磷酸化。
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