Chromatin reader component of the super elongation complex (SEC), a complex required to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA. Specifically recognizes and binds acylated histone H3, with a preference for histone H3 that is crotonylated. Crotonylation marks active promoters and enhancers and confers resistance to transcriptional repressors. Recognizes and binds histone H3 crotonylated at 'Lys-9' (H3K9cr), and with slightly lower affinity histone H3 crotonylated at 'Lys-18' (H3K18cr). Also recognizes and binds histone H3 acetylated and butyrylated at 'Lys-9' (H3K9ac and H3K9bu, respectively), but with lower affinity than crotonylated histone H3. In the SEC complex, MLLT3 is required to recruit the complex to crotonylated histones. Recruitment of the SEC complex to crotonylated histones promotes recruitment of DOT1L on active chromatin to deposit histone H3 'Lys-79' methylation (H3K79me). Plays a key role in hematopoietic stem cell (HSC) maintenance by preserving, rather than confering, HSC stemness. Acts by binding to the transcription start site of active genes in HSCs and sustaining level of H3K79me2, probably by recruiting DOT1L. Component of the super elongation complex (SEC), at least composed of EAF1, EAF2, CDK9, MLLT3/AF9, AFF (AFF1 or AFF4), the P-TEFb complex and ELL (ELL, ELL2 or ELL3) (By similarity). Interacts with BCOR (By similarity). Interacts with CBX8 (PubMed:11439343). Interacts with ALKBH4 (By similarity). Colocalizes with acylated histone H3. H3 Colocalizes with histone H3 crotonylated at 'Lys-18' (H3K18cr). Ubiquitously expressed. Strong expression in the spleen. The YEATS domain specifically recognizes and binds acylated histones, with a marked preference for histones that are crotonylated. Also binds histone H3 acetylated at 'Lys-9' (H3K9ac), but with lower affinity. Binds crotonylated lysine through a non-canonical pi-pi-pi stacking mechanism. The YEATS domain also binds DNA.