Identification and mapping of post-transcriptional modifications on the HIV-1 antisense transcript Ast in human cells

(A) LC-MS based detection of [Ψ]ACAGp from Ast RNA. Extracted ion chromatogram for m/z 841.596 (top panel). Tandem mass spectrum of oligonucleotide anion (m/z 841.596) with all the observed sequence informative fragment ions (bottom panel). Fragmentation pattern of the oligomer is depicted. (B) LC-MS based detection of UCC[I]CC > p from Ast RNA. Extracted ion chromatogram for m/z 927.104 (top panel). Tandem mass spectrum of oligonucleotide anion (m/z 927.104) with all the observed sequence informative fragment ions (bottom panel). Fragmentation pattern of the oligomer is depicted.