GAIP, A PROTEIN THAT SPECIFICALLY INTERACTS WITH THE TRIMERIC G-PROTEIN G-ALPHA(I3), IS A MEMBER OF A PROTEIN FAMILY WITH A HIGHLY CONSERVED CORE DOMAIN
GAIP, A PROTEIN THAT SPECIFICALLY INTERACTS WITH THE TRIMERIC G-PROTEIN G-ALPHA(I3), IS A MEMBER OF A PROTEIN FAMILY WITH A HIGHLY CONSERVED CORE DOMAIN
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DOI：
10.1073/pnas.92.25.11916
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发表时间：
1995-12-05
影响因子：
11.1
通讯作者：
FARQUHAR, MG
中科院分区：
文献类型：
--
作者：
DEVRIES, L;MOUSLI, M;FARQUHAR, MG
使用酵母双杂交系统，我们已经确定了一种人类蛋白质，GAIP（G α相互作用蛋白），它特异性地与异源三聚体GTP结合蛋白G α（i3）相互作用。通过体外翻译的G α（i3）与GAIP-谷胱甘肽S-转移酶融合蛋白的特异性结合来验证相互作用。GAIP是一种小蛋白（217个氨基酸，24 kDa），含有两个潜在的蛋白激酶C磷酸化位点和七个酪蛋白激酶2磷酸化位点。GAIP与先前鉴定的两种人类蛋白质GOS 8和1 R20、两种秀丽隐杆线虫蛋白质C05B5.7和C29H12.3以及构巢曲霉中的FLBA基因产物具有高度同源性，所有这些蛋白质的功能都是未知的。还发现了与酿酒酵母中已知与酵母G α亚基（Gpa 1）相互作用的SST 2基因产物的显著同源性。一个高度保守的核心结构域的125个氨基酸的特点是这个家庭的蛋白质。对缺失突变体的分析表明，核心结构域是GAIP与G α（i3）相互作用的位点。GAIP可能是一种早期诱导磷蛋白，因为其cDNA在其3 '非翻译区含有早期应答基因特征性的TTTTGT序列。通过北方分析，GAIP的1.6-kb mRNA在肺、心脏、胎盘和肝脏中最丰富，在脑、骨骼肌、胰腺和肾脏中非常低。GAIP似乎只与G alpha（i3）相互作用，因为它不与G alpha（i2）和G alpha（q）相互作用。GAIP和Sst 2与G α亚基相互作用并共享一个共同结构域的事实表明，GAIP家族的其他成员也通过125个氨基酸的核心结构域与G α亚基相互作用。
Using the yeast two-hybrid system we have identified a human protein, GAIP (G Alpha Interacting Protein), that specifically interacts with the heterotrimeric GTP-binding protein G alpha(i3). Interaction was verified by specific binding of in vitro-translated G alpha(i3) with a GAIP-glutathione S-transferase fusion protein. GAIP is a small protein (217 amino acids, 24 kDa) that contains two potential phosphorylation sites for protein kinase C and seven for casein kinase 2. GAIP shows high homology to two previously identified human proteins, GOS8 and 1R20, two Caenorhabditis elegans proteins, C05B5.7 and C29H12.3, and the FLBA gene product in Aspergillus nidulans-all of unknown function. Significant homology was also found to the SST2 gene product in Saccharomyces cerevisiae that is known to interact with a yeast G alpha subunit (Gpa1). A highly conserved core domain of 125 amino acids characterizes this family of proteins. Analysis of deletion mutants demonstrated that the core domain is the site of GAIP's interaction with G alpha(i3). GAIP is likely to be an early inducible phosphoprotein, as its cDNA contains the TTTTGT sequence characteristic of early response genes in its 3'-untranslated region. By Northern analysis GAIP's 1.6-kb mRNA is most abundant in lung, heart, placenta, and liver and is very low in brain, skeletal muscle, pancreas, and kidney. GAIP appears to interact exclusively with G alpha(i3), as it did not interact with G alpha(i2) and G alpha(q). The fact that GAIP and Sst2 interact with G alpha subunits and share a common domain suggests that other members of the GAIP family also interact with G alpha subunits through the 125-amino-acid core domain.