A 35-kDa protein binding to a cytosine-rich strand of hypervariable minisatellite DNA.
A minisatellite-binding protein, Msbp-4, with a molecular mass of 35 kDa has been purified from mouse tumor cells that binds to hypervariable Pc-1 and Pc-2 minisatellites. The binding is much more efficient than that to genetically stable minisatellite homologues. As assayed by Southwestern analysis, Msbp-4 favors multiple copies of the Pc-2 repeat sequence GGCAGGA and requires the cytosine-rich single strand for the binding. The activity is also present in extracts from mouse testis but not from liver. The phosphatase treatment revealed that Msbp-4 is phosphorylated and may have a regulatory function, because dephosphorylation affects the activity and specificity of the binding. Sequence preference is demonstrated by a competition experiment using single-base substitution mutants. Thus, the binding properties of Msbp-4 observed here lead to an implication that the protein-DNA complexes result in formation of a single-stranded DNA loop of the G-rich strand in the minisatellite which may enhance the ability of the minisatellite to undergo recombination.
Yamazaki
H
H
First Department of Biochemistry, Niigata University School of Medicine, Japan.
Nomoto
S
S
Mishima
Y
Y
Kominami
R
R
D000818:Animals; D015139:Blotting, Southern; D015153:Blotting, Western; D003596:Cytosine / Q000378:metabolism*; D004276:DNA, Satellite / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010766:Phosphorylation; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D013737:Testis / Q000378:metabolism
D004276:DNA, Satellite; D004268:DNA-Binding Proteins; D003596:Cytosine