Characterization of SAF-A, a novel nuclear DNA binding protein from HeLa cells with high affinity for nuclear matrix/scaffold attachment DNA elements.
We identified four proteins in nuclear extracts from HeLa cells which specifically bind to a scaffold attachment region (SAR) element from the human genome. Of these four proteins, SAF-A (scaffold attachment factor A), shows the highest affinity for several homologous and heterologous SAR elements from vertebrate cells. SAF-A is an abundant nuclear protein and a constituent of the nuclear matrix and scaffold. The homogeneously purified protein is a novel double stranded DNA binding protein with an apparent molecular weight of 120 kDa. SAF-A binds at multiple sites to the human SAR element; competition studies with synthetic polynucleotides indicate that these sites most probably reside in the multitude of A/T-stretches which are distributed throughout this element. In addition we show by electron microscopy that the protein forms large aggregates and mediates the formation of looped DNA structures.
Romig
H
H
Department of Biology, University of Konstanz, Germany.
Fackelmayer
F O
FO
Renz
A
A
Ramsperger
U
U
Richter
A
A
D000818:Animals; D002874:Chromosome Mapping; D004247:DNA / Q000378:metabolism / Q000648:ultrastructure; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D015530:Nuclear Matrix / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D013045:Species Specificity
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D004247:DNA; D004264:DNA Topoisomerases, Type I