Sin3A Associated Protein 18kDa (SAP18)

Histone acetylation plays a key role in the regulation of eukaryotic gene expression. Histone acetylation and deacetylation are catalyzed by multisubunit complexes. SAP18 is a component of the histone deacetylase complex, which includes SIN3, SAP30, HDAC1, HDAC2, RbAp46, RbAp48, and other polypeptides. This protein directly interacts with SIN3 and enhances SIN3-mediated transcriptional repression when tethered to the promoter.The predicted 153-amino acid SAP18 protein is 49% identical to a C. elegans SAP18 homolog. SAP18 has a molecular mass of 18 kD by SDS-PAGE.SAP18 directly interacts with SIN3 and enhances SIN3-mediated transcriptional repression. They observed that SAP18 directs the formation of a repressive complex when tethered to the promoter. SAP18 was expressed in all tissues analyzed.