REGIONS OF THE ALPHA-1-ADRENERGIC RECEPTOR INVOLVED IN COUPLING TO PHOSPHATIDYLINOSITOL HYDROLYSIS AND ENHANCED SENSITIVITY OF BIOLOGICAL FUNCTION
REGIONS OF THE ALPHA-1-ADRENERGIC RECEPTOR INVOLVED IN COUPLING TO PHOSPHATIDYLINOSITOL HYDROLYSIS AND ENHANCED SENSITIVITY OF BIOLOGICAL FUNCTION
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DOI：
10.1073/pnas.87.8.2896
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发表时间：
1990-04-01
影响因子：
11.1
通讯作者：
LEFKOWITZ, RJ
中科院分区：
文献类型：
--
作者：
COTECCHIA, S;EXUM, S;LEFKOWITZ, RJ
通过研究由重组DNA技术构建的突变受体的生物学功能，确定了在GTP结合蛋白（G蛋白）介导的磷脂酶C活化中重要的仓鼠α 1-肾上腺素能受体（α 1AR）的区域。由β 2-肾上腺素能受体（β 2AR）组成的嵌合受体，其中假定的α 1AR的第三胞质环已被置于其中，与天然α 1AR一样有效地激活磷脂酰肌醇代谢，在其胞质尾中缺少最后47个残基的截短的α 1AR也是如此。α 1AR的第三胞质环的中间部分或胞质尾的N-末端部分中β 2AR氨基酸序列的取代引起受体与磷脂酶C偶联的显著降低。在第三胞质环的C末端中的两个残基的保守取代（Ala 293 →Leu，Lys 290. fwdarw. His）将激动剂刺激磷脂酰肌醇代谢的效力提高了多达2个数量级。这些数据表明（i）决定与磷脂酰肌醇代谢偶联的α 1AR区域与先前显示的参与β 2AR与腺苷酸环化酶刺激偶联的区域相似，和（ii）G蛋白偶联受体的点突变可引起生物反应敏感性的显著增加。
Regions of the hamster .alpha.1-adrenergic receptor (.alpha.1AR) that are important in GTP-binding protein (G protein)-mediated activation of phospholipase C were determined by studying the biological functions of mutant receptors constructed by recombinant DNA techniques. A chimeric receptor consisting of the .beta.2-adrenergic receptor (.beta.2AR) into which the putative third cytoplasmic loop of the .alpha.1AR had been placed activated phosphatidylinositol metabolism as effectively as the native .alpha.1AR, as did a truncated .alpha.1AR lacking the last 47 residues in its cytoplasmic tail. Substitutions of .beta.2AR amino acid sequence in the intermediate portions of the third cytoplasmic loop of the .alpha.1AR or the N-terminal portion of the cytoplasmic tail caused marked decreases in receptor coupling to phospholipase C. Conservative substitutions of two residues in the C terminus of the third cytoplasmic loop (Ala293 .fwdarw. Leu, Lys290 .fwdarw. His) increased the potency of agonists for stimulating phosphatidylinositol metabolism by up to 2 orders of magnitude. These data indicate (i) that the regions of the .alpha.1AR that determine coupling to phosphatidylinositol metabolism are similar to those previously shown to be involved in coupling of .beta.2AR to adenylate cyclase stimulation and (ii) that point mutations of a G-protein-coupled receptor can cause remarkable increases in sensitivity of biological response.