Promoter binding proteins of an active human L1 retrotransposon

Human Long Interspersed elements (LINEs or L1Hs elements) are a highly repetitive class of DNA sequences which are dispersed by retrotransposition. Full length L1Hs transcripts and L1-encoded proteins have been shown by others to be present in NTera2D1 and other related teratocarcinoma cell lines. Using standard methods for the identification of DNA binding proteins we identified two proteins or complexes of proteins which specifically bind to the L1Hs promoter region and are qualitatively different between NTera2D1 and HeLa cell nuclear extracts. These proteins represent candidates for the factors controlling the differential expression of L1 sequences.