| A 1797 bp human EcoRI satellite II DNA sequence was cloned in vectors containing the thymidine kinase gene (HSV-1 tk) and the neomycin resistance gene, and introduced in a cell line deficient for these genes. We have observed that the electroporation efficiency of these plasmids depends on the location and/or the orientation of the satellite sequences within the transfected plasmid. Only one plasmid, pCFD1 containing one satellite fragment close to the neo gene, inhibited the formation of TK;Moreover, we have detected (both in nuclear and partially purified HeLa whole cell extracts) the presence of proteins that specifically bind the human 1797 bp satellite II DNA sequence. Four proteins with molecular weights of 100, 93, 77 and 34 kDa were identified and named Satellite DNA-binding protein, Sbp-1, -2, -3 and -4, respectively. The function of these proteins is, as yet, unknown. |
