Identification and Analysis of Native Nucleosomal Histone Acetyltransferase Complexes

Histones are the predominant protein component of chromatin and are subject to a variety of post-translational modifications. Of these, acetylation of the amino-terminal tails of core histones is most intensively studied and is linked to chromatin assembly, the regulation of gene expression, cell cycle progression and cellular transformation (1 ). Characterization of the enzymes responsible for histone acetylation provides a handle for directly studying such histone modifications in these processes. Two classes of histone acetyltransferases (HATs) have been described; cytoplasmic type B HATs acetylate free histones for subsequent assembly into chromatin (2 ) and nuclear type A HATs, which mediate transcription related acetylation of chromosomal histones (3 ).