Multilevel interrogation of H3.3 reveals a primordial role in transcription regulation.

"all ms files used in this study were deposited at massive ( http://massive ucsd edu ) and assigned the identifier msv000090060.; all ms files generated in this study were deposited at massive ( http://massive ucsd edu ) and assigned the identifier msv000090060."

"Declarations Ethics approval and consent to participateNot applicable. Competing interestsThe authors declare no competing interests. Competing interests The authors declare no competing interests."

"Funding The Fillingham and Lambert laboratories were supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants [RGPIN-2020-07036, RGPIN-2017-06124]. The Fillingham laboratory was also supported by a grant from the Ryerson University Health Research Fund and the Ryerson University Faculty of Science Dean's Research Fund; J.-P.L. holds a Junior 1 salary award from the Fonds de Recherche du Québec-Santé (FRQ-S) and was also supported through a John R. Evans Leaders Fund from the Canada Foundation for Innovation [37454, 41426]. The Pearlman laboratory was supported by the Canadian Institutes of Health Research (CIHR) [MOP13347]; NSERC Discovery Grant [539509]. The Greenblatt laboratory was supported by the CIHR Foundation Grant [FDN-154338]. H.L was supported by a Canada Graduate Scholarship from NSERC."