ABA-spermine cross-linking at the tip of helix H38

Copyright information:Taken from "Localization of spermine binding sites in 23S rRNA by photoaffinity labeling: parsing the spermine contribution to ribosomal 50S subunit functions"Nucleic Acids Research 2005;33(9):2792-2805.Published online 16 May 2005PMCID:PMC1129027.© The Author 2005. Published by Oxford University Press. All rights reserved Naked 23S rRNA was photolabeled with ABA-spermine, and then was monitored by primer-extension analysis. The primer for the reverse transcriptase reaction was complementary to 23S rRNA positions 962–978. U, A, G and C are dideoxy sequencing lanes. Lane 0, control (non-photolabeled sample); lane 1, sample photolabeled with 50 μM ABA-spermine in the presence of translation factors; lane 3, sample photolabeled with 300 μM ABA-spermine in the absence of translation factors; lanes 2 and 4, samples like those used in lanes 1 and 3, respectively, but photolabeled in the simultaneous presence of spermine in excess; lane 5, sample modified by DMS; lanes 6 and 7, samples treated as those in lanes 1 and 3, respectively, and then modified by DMS. The stops of reverse transcriptase reaction due to ABA-spermine cross-linking are indicated by arrows.