Role of the glucagon receptor COOH-terminal domain in glucagon-mediated signaling and receptor internalization
Role of the glucagon receptor COOH-terminal domain in glucagon-mediated signaling and receptor internalization
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DOI：
10.2337/diabetes.46.9.1400
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发表时间：
1997-09-01
期刊：
影响因子：
7.7
通讯作者：
Rossomando, AJ
中科院分区：
文献类型：
--
作者：
Buggy, JJ;Heurich, RO;Rossomando, AJ
胰高血糖素与其肝脏受体的结合可导致一系列效应，包括cAMP在细胞内的积聚，细胞内钙离子的动员，以及胰高血糖素及其受体内吞进入细胞内的囊泡。在这项研究中，我们开始确定人胰高血糖素受体的COOH末端尾巴在胰升糖素刺激的信号转导和受体内化中的功能作用。我们创造并在中国仓鼠卵巢(CHO)细胞中表达了5个截短突变体，其中24、56、62、67和73个氨基酸的COOH末端已被去除。用免疫荧光法检测表达相关截短受体的细胞表面表达、配体结合特性、cAMP和钙离子介导的信号转导特性以及受体内吞作用。此外，还研究了在COOH末端尾部含有7个丝氨酸到丙氨酸突变的突变受体。我们的结果表明：1)COOH末端尾部的一个区域是细胞表面正常表达所必需的，2)COOH末端的62个氨基酸是配体结合、cAMP积累或钙动员所不需要的，3)COOH末端尾部的磷酸化对于高血糖素刺激的受体内吞是至关重要的。
The binding of glucagon to its hepatic receptor is known to result in a number of effects, including the intracellular accumulation of cAMP, the mobilization of intracellular Ca2+, and the endocytosis of glucagon and its receptor into intracellular vesicles. In this study, are begin to define the functional role of the COOH-terminal tail of the human glucagon receptor in glucagon-stimulated signal transduction and receptor internalization. We have created and expressed in Chinese hamster ovary (CHO) cells five truncation mutants in which the COOH-terminal 24, 56, 62, 67, and 73 amino acids have been removed. Cells expressing relevant truncated receptors were assayed for cell surface expression by immunofluorescence, for Ligand-binding properties, for cAMP and Ca2+-mediated signal transduction properties, and for receptor endocytosis. In addition, a mutant receptor containing seven serine-to-alanine mutations in the COOH-terminal tail was studied. Our results reveal the following: 1) a region of the COOH-terminal tail that is required for proper cell surface expression, 2) the COOH-terminal 62 amino acids, which comprise the majority of the tail, are not required for ligand binding, cAMP accumulation, or Ca2+ mobilization, and 3) phosphorylation of the COOH-terminal tail is crucial for glucagon-stimulated receptor endocytosis.