Ribonuclease and high salt sensitivity of the ribonucleoprotein complex formed by the human LINE-1 retrotransposon.
P40 is encoded by the first open reading frame of the human LINE-1 retrotransposon and is found in a large cytoplasmic ribonucleoprotein (RNP) complex, the p40 RNP-complex, in association with LINE-1 RNA(s) in human teratocarcinoma cell lines. We report here investigations on the stability of the p40 RNP-complex against various nucleases and high salt (0.5 M NaCl) treatment. The results indicate that (1) the p40 RNP-complex is dissociated after ribonuclease or high salt treatment, (2) DNase I does not disrupt the complex, (3) after dissociation of the complex, p40 maintain protein-protein interactions but in smaller complexes, and (4) p40 is not associated with the LINE-1 RNA(s) after high salt treatment. These observations suggest that the RNA molecule(s) is(are) essential for the stability of the large p40 complex and that the complex has a structure which allows various nucleases to reach the RNA. These features are distinct from those of typical virus and virus-like particles of retroviruses and other retrotransposons, respectively. Together with the fact that no significant sequence homology exists between p40 and the gag and gag-like proteins, it is likely that the p40 RNP-complex is structurally different from the typical virus and virus-like particles.
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Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Singer
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D015153:Blotting, Western; D003432:Cross-Linking Reagents; D003850:Deoxyribonuclease I; D006801:Humans; D012091:Repetitive Sequences, Nucleic Acid; D018626:Retroelements / Q000187:drug effects; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000737:chemistry*; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D013724:Teratoma; D014407:Tumor Cells, Cultured
D003432:Cross-Linking Reagents; D018626:Retroelements; D012261:Ribonucleoproteins; D012462:Saline Solution, Hypertonic; D012260:Ribonucleases; D003850:Deoxyribonuclease I; D012259:Ribonuclease, Pancreatic