Extended Data Figure 1. Bioorthogonal labeling by 5-PT identifies H3 serotonylation in chromatin.
a, Structures of 5-HT and 5-PT in transamidation reactions. b, Immunofluorescence images (Scale bars equal 500 μm) of intracellular 5-PT in HeLa cells (bottom) after exogenous application of the molecule (vs. vehicle, top). Intracellular 5-PT was imaged in fixed cells after chemical labeling with Alexa Fluor 488 azide. DAPI was used as a nuclear co-stain. Results confirmed in ≥ 2 independent experiments. c, Cell vs. lysate donor competition assays indicating that application of excess 5-HT to live HeLa cells, but not to processed lysates, prior to chemical labeling and 5-PT-based pulldowns results in loss of H3 signal post-IP. Input and IP WBs are shown. d, Cellular fractionation analysis (WB) identifying H3 serotonylation post-IP in HeLa cell chromatin, but not in soluble nuclear or cytosolic fractions. Input and IP WBs are shown. H3 results confirmed in ≥ 3 independent experiments.