A gain-of-function polymorphism in a G-protein coupling domain of the human β1-adrenergic receptor
A gain-of-function polymorphism in a G-protein coupling domain of the human β1-adrenergic receptor
复制标题
DOI：
10.1074/jbc.274.18.12670
复制
发表时间：
1999-04-30
影响因子：
4.8
通讯作者：
Liggett, SB
中科院分区：
文献类型：
--
作者：
Mason, DA;Moore, JD;Liggett, SB
β(1)-肾上腺素能受体 (β(1)AR) 是一种关键的细胞表面信号蛋白，在心脏和其他器官中表达，介导交感神经系统儿茶酚胺的作用。在一组正常个体中，已鉴定出人类 β(1)AR 第七跨膜片段附近的细胞内胞质尾部存在多态性。在氨基酸位置389处，可以发现Gly或Arg（等位基因频率分别为0.26和0.74），前者先前被认为是人类野生型β(1)AR。使用定点诱变来模拟这两种变体，CHW-1102 细胞被永久转染以表达 Gly-389 和 Arg-389 受体。在表达匹配的功能研究中，Arg-389 受体的腺苷酸环化酶活性基础水平略高（10.7 +/- 1.2 与 6.1 +/- 0.4 pmol/min/mg），然而，最大与 Gly-389 受体相比，Arg-389 的异丙肾上腺素刺激水平明显更高（63.3 +/- 6.1 对比 20.9 +/- 2.0 pmol/min/mg），激动剂促进的 [S-35]鸟苷 5'-O-（硫代三磷酸）结合也随 Arg-389 受体增加，与增强的 G(s) 偶联一致，并且增加腺苷酸环化酶激活。在缺乏鸟苷 5'-(β,γ-亚氨基)三磷酸的情况下进行的激动剂竞争研究中，Gly-389 受体无法解析高亲和力结合，而 Arg-389 则显示出激动剂高亲和力受体复合物的积累 (R-H = 26%)。总而言之，这些数据表明，人β(1)AR的这种多态性变异导致受体-G(s)相互作用的改变以及功能性信号转导结果，与其在假定的G蛋白结合域中的定位一致。该位点的 β(1)AR 遗传变异可能是心血管和其他疾病中病理生理学特征或对治疗性 βAR 激动剂和拮抗剂的反应的个体差异的基础。
The beta(1)-adrenergic receptor (beta(1)AR) is a key cell surface signaling protein expressed in the heart and other organs that mediates the actions of catecholamines of the sympathetic nervous system. A polymorphism in the intracellular cytoplasmic tail near the seventh transmembrane-spanning segment of the human beta(1)AR has been identified in a cohort of normal individuals. At amino acid position 389, Gly or Arg can be found (allele frequencies 0.26 and 0.74, respectively), the former previously considered as the human wild-type beta(1)AR. Using site-directed mutagenesis to mimic the two variants, CHW-1102 cells were permanently transfected to express the Gly-389 and Arg-389 receptors, In functional studies with matched expression, the Arg-389 receptors had slightly higher basal levels of adenylyl cyclase activities (10.7 +/- 1.2 versus 6.1 +/- 0.4 pmol/min/mg), However, maximal isoproterenol-stimulated levels were markedly higher for the Arg-389 as compared to the Gly-389 receptor (63.3 +/- 6.1 versus 20.9 +/- 2.0 pmol/min/mg), Agonist-promoted [S-35]guanosine 5'-O-(thiotriphosphate) binding was also increased with the Arg-389 receptor consistent with enhanced coupling to G(s) and increased adenylyl cyclase activation. In agonist competition studies carried out in the absence of guanosine 5'-(beta,gamma-imido)triphosphate, high affinity binding could not be resolved with the Gly-389 receptor, whereas Arg-389 displayed an accumulation of the agonist high affinity receptor complex (R-H = 26%). Taken together, these data indicate that this polymorphic variation of the human beta(1)AR results in alterations of receptor-G(s) interaction with functional signal transduction consequences, consistent with its localization in a putative G-protein binding domain. The genetic variation of beta(1)AR at this locus may be the basis of interindividual differences in pathophysiologic characteristics or in the response to therapeutic beta AR agonists and antagonists in cardiovascular and other diseases.