SUBSTITUTION OF 3 AMINO-ACIDS SWITCHES RECEPTOR SPECIFICITY OF G(Q)ALPHA TO THAT OF G(I)ALPHA
SUBSTITUTION OF 3 AMINO-ACIDS SWITCHES RECEPTOR SPECIFICITY OF G(Q)ALPHA TO THAT OF G(I)ALPHA
复制标题
DOI：
10.1038/363274a0
复制
发表时间：
1993-05-20
期刊：
影响因子：
64.8
通讯作者：
BOURNE, HR
中科院分区：
文献类型：
--
作者：
CONKLIN, BR;FARFEL, Z;BOURNE, HR
激动剂结合受体通过催化GTP 1 -5取代与α亚基结合的GDP来激活异源三聚体（α-γ）G蛋白。α-亚基C末端的突变6，7，其通过百日咳毒素催化的ADP核糖基化的共价修饰8，针对其的肽特异性抗体9 -11，和模拟C末端序列的肽12，都抑制受体介导的G蛋白活化。在逻辑上的预测-α-亚单位C-末端的特定氨基酸残基可以决定单个G蛋白区分特定受体子集的能力-迄今为止还没有经过实验验证。不同的激素受体特异性地激活G（q）或G（i），其α-亚基（α（q）或α（i））分别刺激磷脂酰肌醇特异性磷脂酶C或抑制腺苷酸环化酶1 -5。在这里，我们用α（i2）的相应残基替换α（q）的C-末端氨基酸，以产生α（q）/α（i2）嵌合体，其可以介导通过另外仅与G（i）偶联的受体对磷脂酶C的刺激。最少三个α（i2）氨基酸，包括距C末端三个残基的甘氨酸，足以切换α（q）/α（i2）嵌合体的受体特异性。我们提出，C-末端的转折，集中在这个甘氨酸，在指定G（i）/G（o）/G（z）家族中的G蛋白的受体相互作用中起着重要的作用。
AGONIST-BOUND receptors activate heterotrimeric (alphabetagamma) G proteins by catalysing replacement of GDP bound to the alpha-subunit by GTP1-5. Mutations in the C terminus of the alpha-subunit6,7, its covalent modification by pertussis toxin-catalysed ribosylation of ADP8, peptide-specific antibodies directed against it9-11, and peptides mimicking C-terminal sequences12, all inhibit receptor-mediated activation of G proteins. The logical prediction-that specific amino-acid residues at the C-termini of alpha-subunits can determine the abilities of individual G proteins to discriminate among specific subsets of receptors-has so far not been tested experimentally. Different hormone receptors specifically activate G(q) or G(i), whose alpha-subunits (alpha(q) or alpha(i)) stimulate phosphatidylinositol-specific phospholipase C or inhibit adenylyl cyclase, respectively1-5. Here we replace C-terminal amino acids of alpha(q) with the corresponding residues of alpha(i2) to create alpha(q)/alpha(i2) chimaeras that can mediate stimulation of phospholipase C by receptors otherwise coupled exclusively to G(i). A minimum of three alpha(i2) amino acids, including a glycine three residues from the C terminus, suffices to switch the receptor specificity of the alpha(q)/alpha(i2) chimaeras. We propose that a C-terminal turn, centred on this glycine, plays an important part in specifying receptor interactions of G proteins in the G(i)/G(o)/G(z) family.