Proteins Binding to Cytosine-Rich Strand of Hypervariable Minisatellite DNA

点击翻译按钮获取中文摘要

Two nuclear proteins, p35a and p35b, with a molecular weight of 35 kDa were detected that bound to hypervariable Pc-1 and Pc-2 minisatellites more efficiently than to genetically stable minisatellite homologues. Pc-1 and Pc-2 DNA probes used consisted of five and six repeats of GGCAG and AGGCAGG sequences, respectively. The binding required the presence of multiple of multiple repeat copies and of cytosine-rich single-stranded regions of the Pc-1 and Pc-2 sequences. p35a was detected in extracts from FM3A cells, mouse testis and liver, whereas p35b was found in the FM3A and liver extracts but not in the testis. Both proteins bound to the double-strands of Pc-1 and Pcー2 with single-strand regions, but only p35a was able to bind to their cytosine-rich single-strands. The protein-DNA complexes are assumed to result in forming a structure with single-stranded DNA loops in the DNA string of aminisatellite, which may enhance the ability of the minisatellite to undergo recombination.