Functions as component of the transcription regulatory histone acetylation (HAT) complexes SAGA, SALSA and ADA. SAGA is involved in RNA polymerase II-dependent transcriptional regulation of approximately 10% of yeast genes. At the promoters, SAGA is required for recruitment of the basal transcription machinery. SAGA acetylates nucleosomal histone H3 to some extent (to form H3K9ac, H3K14ac, H3K18ac and H3K23ac). SAGA interacts with DNA via upstream activating sequences (UASs). SALSA, an altered form of SAGA, may be involved in positive transcriptional regulation. ADA preferentially acetylates nucleosomal histones H3 (to form H3K14ac and H3K18ac) and H2B. Required for expression of many CAS5-dependent genes. Plays a key role in cell wall integrity, cell adhesion, hyphal development and pathogenesis. Component of SAGA complex, SALSA complex, and ADA complex.