Department of Biochemistry, Faculty of Science, Ege University, Izmir, Turkey.
Biochem Biophys Res Commun. 2011 Aug 12;411(4):792-7. doi: 10.1016/j.bbrc.2011.07.029. Epub 2011 Jul 20.
The vast majority of physiological processes in living cells are mediated by protein-protein interactions often specified by particular protein sequence motifs. PDZ domains, composed of 80-100 amino acid residues, are an important class of interaction motif. Among the PDZ-containing proteins, glutaminase interacting protein (GIP), also known as Tax Interacting Protein TIP-1, is unique in being composed almost exclusively of a single PDZ domain. GIP has important roles in cellular signaling, protein scaffolding and modulation of tumor growth and interacts with a number of physiological partner proteins, including Glutaminase L, β-Catenin, FAS, HTLV-1 Tax, HPV16 E6, Rhotekin and Kir 2.3. To identify the network of proteins that interact with GIP, a human fetal brain cDNA library was screened using a yeast two-hybrid assay with GIP as bait. We identified brain-specific angiogenesis inhibitor 2 (BAI2), a member of the adhesion-G protein-coupled receptors (GPCRs), as a new partner of GIP. BAI2 is expressed primarily in neurons, further expanding GIP cellular functions. The interaction between GIP and the carboxy-terminus of BAI2 was characterized using fluorescence, circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy assays. These biophysical analyses support the interaction identified in the yeast two-hybrid assay. This is the first study reporting BAI2 as an interaction partner of GIP.
在活细胞中，绝大多数生理过程都是通过蛋白质-蛋白质相互作用来介导的，而这些相互作用通常由特定的蛋白质序列基序来指定。PDZ 结构域由 80-100 个氨基酸残基组成，是一类重要的相互作用基序。在含有 PDZ 结构域的蛋白质中，谷氨酸酶相互作用蛋白（GIP），也称为 Tax 相互作用蛋白 TIP-1，是独一无二的，它几乎完全由一个 PDZ 结构域组成。GIP 在细胞信号转导、蛋白质支架以及调节肿瘤生长方面具有重要作用，并且与许多生理伴侣蛋白相互作用，包括谷氨酸酶 L、β-连环蛋白、FAS、HTLV-1 Tax、HPV16 E6、Rhotekin 和 Kir 2.3。为了鉴定与 GIP 相互作用的蛋白质网络，我们使用 GIP 作为诱饵，通过酵母双杂交筛选了人类胎儿大脑 cDNA 文库。我们鉴定了脑特异性血管生成抑制剂 2（BAI2），一种黏附 G 蛋白偶联受体（GPCRs）的成员，作为 GIP 的一个新伴侣。BAI2 主要在神经元中表达，进一步扩展了 GIP 的细胞功能。使用荧光、圆二色性（CD）和核磁共振（NMR）光谱分析测定了 GIP 和 BAI2 羧基末端之间的相互作用。这些生物物理分析支持在酵母双杂交测定中鉴定的相互作用。这是首次报道 BAI2 作为 GIP 相互作用伴侣的研究。
