Reddy C D, Dasgupta P, Saikumar P, Dudek H, Rauscher F J, Reddy E P
Fels Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania 19140.
Oncogene. 1992 Oct;7(10):2085-92.
The Max protein forms a heterodimeric complex with the Myc family of proteins and binds to DNA in a sequence-specific manner. We investigated the role of the helix-loop-helix (HLH), leucine zipper (LZ) and basic domains of Max in protein complex formation, DNA-binding activity and transcriptional regulation. We mutagenized the basic, HLH and LZ domains of Max and studied the ability of the normal and mutant proteins to bind to DNA as both homo- and heterodimers and their ability to heterodimerize with Myc. Helix-1 and helix-2 regions of Max were found to be critical for homodimer formation and subsequent DNA binding, while the LZ was essential for heterodimer formation. In transient transfection assays the Myc protein functioned as a transcriptional activator while Max protein repressed the trans-activation observed with Myc.
Max蛋白与Myc家族蛋白形成异源二聚体复合物，并以序列特异性方式结合DNA。我们研究了Max的螺旋-环-螺旋（HLH）、亮氨酸拉链（LZ）和碱性结构域在蛋白复合物形成、DNA结合活性及转录调控中的作用。我们对Max的碱性、HLH和LZ结构域进行诱变，研究正常和突变蛋白作为同二聚体和异二聚体结合DNA的能力，以及它们与Myc形成异二聚体的能力。发现Max的螺旋1和螺旋2区域对同二聚体形成及随后的DNA结合至关重要，而LZ对异二聚体形成必不可少。在瞬时转染实验中，Myc蛋白起转录激活因子的作用，而Max蛋白则抑制Myc所观察到的反式激活作用。
