SAP30 is a subunit of the histone deacetylase complex, and this domain is a zinc-finger. Solution of the structure shows a novel fold comprising two beta-strands and two alpha-helices with the zinc organising centre showing remote resemblance to the treble clef motif. In silico analysis of the structure revealed a highly conserved surface dominated by basic residues. NMR-based analysis of potential ligands for the SAP30 zn-finger motif indicated a strong preference for nucleic acid substrates. The zinc-finger of SAP3 probably functions as a double-stranded DNA-binding motif, thereby expanding the known functions of both SAP30 and the mammalian Sin3 co-repressor complex [1].

1: Solution structure of a novel zinc finger motif in the SAP30 polypeptide of the Sin3 corepressor complex and its potential role in nucleic acid recognition. He Y, Imhoff R, Sahu A, Radhakrishnan I; Nucleic Acids Res. 2009;37:2142-2152. PMID:19223330