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 (PubMed:20159561, PubMed:20471948). Specifically recognizes and binds acetylated and crotonylated histones, with a preference for histones that are crotonylated (PubMed:27105114). Has a slightly higher affinity for binding histone H3 crotonylated at 'Lys-27' (H3K27cr) than 'Lys-20' (H3K9cr20) (PubMed:27105114). Acts as a key chromatin reader in acute myeloid leukemia by recognizing and binding to acetylated histones via its YEATS domain, thereby regulating oncogenic gene transcription. Acylated lysine-binding is specifically inhibited by the tripeptide XL-13m, carrying a 2-furancarbonyl side chain, preventing recruitment to chromatin. 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) (PubMed:20159561, PubMed:20471948, PubMed:22195968). Interacts with ALKBH4 (PubMed:23145062). Component of a SWI/SNF-like EBAFb complex, at least composed of SMARCA4/BRG1/BAF190A, SMARCB1/BAF47/SNF5, ACTL6A/BAF53A, SMARCE1/BAF57, SMARCD1/BAF60A, SMARCD2/BAF60B, SMARCC1/BAF155, SMARCC2/BAF170, ARID1B/BAF250B, MLLT1/ENL and actin (PubMed:12665591). The YEATS domain specifically recognizes and binds acylated histones, with a preference for histones that are crotonylated. A chromosomal aberration involving MLLT1 is associated with acute leukemias. Translocation t(11;19)(q23;p13.3) with KMT2A/MLL1. The result is a rogue activator protein.