Figure 1
(a) LTR-II + III + IV sequence of the G-rich LTR region comprising tracts that fold into three mutually exclusive LTR G4s, i.e. LTR-II, LTR-III and LTR-IV. These three-stacked tetrads G4s are indicated in brackets. G bases in G-tracts or involved in G-quadruplexes are shown in bold. (b) MS/MS spectrum of the precursor ion observed at m/z 1095.46 in the sample mixture from digestion of LTR-II + III + IV G4 sample (see Table 1). Only characteristic y ions are indicated53. The data match the sequence of peptide N326-R350 of hnRNP A2/B1, which is reported on top with the observed fragments. c) Pull-down assay of nuclear extract proteins with wt, mutant G4 LTR-II + III + IV (M) and random (R) sequences, immobilized on agarose beads. Shown is the western blot analysis with an anti-hnRNP A2/B1 antibody. Proteins complexed to the beads-bound LTRs were washed with augmented stringency by increasing the ionic strength of the wash buffer (0.2 and 1 M). The final elution was obtained in denaturing buffer at 95 °C.
