Tanese N, Saluja D, Vassallo M F, Chen J L, Admon A
Department of Microbiology and Kaplan Cancer Center, New York University Medical Center, NY 10016, USA.
Proc Natl Acad Sci U S A. 1996 Nov 26;93(24):13611-6. doi: 10.1073/pnas.93.24.13611.
Transcription factor TFIID is a multiprotein complex composed of the TATA box-binding protein (TBP) and multiple TBP-associated factors (TAFs). TFIID plays an essential role in mediating transcriptional activation by gene-specific activators. Numerous transcriptional activators have been characterized from mammalian cells; however, molecular analysis of the components of mammalian TFIID has been incomplete. Here we describe isolation of cDNAs encoding two TAF subunits of the human transcription factor TFIID. The first cDNA is predicted to encode the C-terminal 947 residues of the 130-kDa human TAF subunit, hTAFII130. The second cDNA encodes the C-terminal 801 residues of the 100-kDa subunit, hTAFII100. Recombinant TAFs expressed in human cells by transient transfections are capable of associating with the endogenous TAFs and TBP to form a TFIID complex in vivo. Protein binding experiments demonstrate that hTAFII130, like its Drosophila homolog dTAFII110, interacts with the glutamine-rich activation domains of the human transcription factor Sp1. Furthermore, hTAFII130 shows reduced binding to the Sp1 mutants with impaired ability to activate transcription, suggesting a role for hTAFII130 as a direct coactivator target for Sp1.
转录因子TFIID是一种多蛋白复合物，由TATA盒结合蛋白（TBP）和多个TBP相关因子（TAFs）组成。TFIID在介导基因特异性激活因子的转录激活过程中起着至关重要的作用。从哺乳动物细胞中已鉴定出许多转录激活因子；然而，对哺乳动物TFIID组分的分子分析尚不完整。在此，我们描述了编码人类转录因子TFIID的两个TAF亚基的cDNA的分离。第一个cDNA预计编码130 kDa人类TAF亚基hTAFII130的C末端947个残基。第二个cDNA编码100 kDa亚基hTAFII100的C末端801个残基。通过瞬时转染在人类细胞中表达的重组TAFs能够与内源性TAFs和TBP结合，在体内形成TFIID复合物。蛋白质结合实验表明，hTAFII130与其果蝇同源物dTAFII110一样，与人转录因子Sp1富含谷氨酰胺的激活结构域相互作用。此外，hTAFII130与激活转录能力受损的Sp1突变体的结合减少，这表明hTAFII130作为Sp1的直接共激活因子靶点发挥作用。
