The detection and purification of a protein that recognizes a line 1 DNA repetitive sequence

A protein which binds specifically to MspI8 (a 454 bp long repeated sequence highly homologous to the 5’ untranslated region (5'UTR) of the LINE 1 sequence) was found and identified in nuclear extracts of rat liver cells. This protein was detected using the electrophoretic mobility shift assay (EMSA) and was purified by Q-Sepharose and DNA affinity chromatography. Its molecular mass was estimated by SDS electrophoresis as 29 kDa. The possibility that this protein (p29) is the rat analogue of human L1PBP-A, specific for the human LINE sequence LPE1, is discussed.