[Heterogeneity of nuclear proteins from HeLa cells specifically binding to the Alu sequence]

Nuclear proteins from HeLa cells specifically binding to the Alu-repeat cloned in the plasmid Blur8 have been studied. 0.35 M nuclear extract proteins have been separated on DEAE-cellulose. The presence of DNA-binding proteins has been found in all fractions by the technique of DNA-binding on nitrocellulose filters. The labelled restricted DNA of the plasmid Blur8 was incubated with the proteins of different fractions with the subsequent identification of specific Alu-protein complexes in polyacrylamide gel at low ionic strength. At least two proteins have been found to have the different affinity to Alu-repeat. Various functions of Alu-repeats and the possibility of their participation in the initiation of DNA replication are discussed.