HPA2: Hpa2 is a member of the Gcn5-related N-acetyltransferase (GNAT) superfamily, a family of enzymes with diverse substrates including histones, other proteins, arylalkylamines and aminoglycosides.As a GNAT superfamily member, this yeast protein was tested in vitro and found to acetylate histones H3 and H4, with a preference for lysine-14 of H3. Hpa2 has a high degree of homology with another yeast GNAT protein, Hpa3, which displayed very poor HAT activity in in vitro assays but did autoacetylate. (1)

Reference
1. Angus-Hill M. L., Dutnall R. N., Tafrov S. T., Sternglanz R. & Ramakrishnan V.Crystal structure of the histone acetyltransferase Hpa2: A tetrameric member of the Gcn5-related N-acetyltransferase superfamily. J Mol Biol294.1311-1325 (1999). PMID: 10600387.