GCN5 also known as KAT2A, GCN5L2 is a histone acetyltransferase (HAT) that functions primarily as a transcriptional activator. GCN5 plays a critical role as a histone acetyltransferase, facilitating the acetylation of lysine residues on histone tails, which leads to chromatin remodeling and the regulation of gene transcription. This function is essential for various cellular processes including cell cycle progression, differentiation, and response to environmental signals. By acetylating histones, GCN5 enhances the accessibility of transcription factors to DNA, promoting active gene expression, whereas counterpart histone deacetylases like HDAC1 and HDAC2 are involved in transcriptional repression.