Characterization of SAF-A, a novel nuclear DNA binding protein from HeLa cells with high affinity for nuclear matrix/scaffold attachment DNA elements
Romig, H.; Fackelmayer, F.O.; Renz, A.; Ramsperger, U.; Richter, A.
EMBO Journal 11(9): 3431-3440
1992
ISSN/ISBN: 0261-4189 PMID: 1324173 Document Number: 400197
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.