1QSM:
reference: Crystal structure of the histone acetyltransferase Hpa2: A tetrameric member of the Gcn5-related N-acetyltransferase superfamily., Angus-Hill ML, Dutnall RN, Tafrov ST, Sternglanz R, Ramakrishnan V, J Mol Biol 1999 Dec 17;294(5):1311-25. PMID: 10600387

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).