Dempsey L A, Hanakahi L A, Maizels N
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
J Biol Chem. 1998 Oct 30;273(44):29224-9. doi: 10.1074/jbc.273.44.29224.
The B cell-specific, sequence-specific duplex DNA-binding protein LR1 is a transcriptional activator and may also function in heavy chain class switch recombination. LR1 is composed of two polypeptides, a 106-kDa subunit that is nucleolin, and a 45-kDa subunit that we now show to be a specific isoform of hnRNP D. hnRNP D and nucleolin both contain canonical RNA binding domains (RBDs also called RRMs) and Arg-Gly-Gly (RGG) motifs. Although these motifs are not commonly associated with sequence-specific recognition of duplex DNA, nonetheless LR1 binds duplex DNA with high affinity (KD = 1.8 nM) and clear sequence specificity. Two RBD-RGG proteins can therefore combine to produce a sequence-specific duplex DNA-binding protein.
B细胞特异性、序列特异性双链DNA结合蛋白LR1是一种转录激活因子，也可能在重链类别转换重组中发挥作用。LR1由两种多肽组成，一种是106 kDa的亚基即核仁素，另一种是45 kDa的亚基，我们现在证明它是hnRNP D的一种特定异构体。hnRNP D和核仁素都含有典型的RNA结合结构域（RBDs，也称为RRMs）和精氨酸-甘氨酸-甘氨酸（RGG）基序。尽管这些基序通常与双链DNA的序列特异性识别无关，但LR1仍以高亲和力（KD = 1.8 nM）和明确的序列特异性结合双链DNA。因此，两种RBD-RGG蛋白可以结合产生一种序列特异性双链DNA结合蛋白。
