Sin3A Associated Protein 130kDa (SAP130)

SAP130 is a subunit of the histone deacetylase -dependent SIN3A corepressor complex. The deduced 1,048-amino acid protein has proline-rich domains in its N- and C-terminal halves. In vitro translation resulted in a protein with an apparent molecular mass of 130 kD. Northern blot analysis detected a 4.4-kb transcript in all human cell lines examined.SAP130 also bound SIN3A lacking the HDAC-interacting domain, suggesting the presence of a second binding site in the N-terminal half of SIN3A. When targeted to DNA, both SAP130 and SAP180 repressed transcription. SIN3A and HDAC1 bound to the C terminus of SAP130, and all truncated SAP130 proteins able to bind SIN3A and HDAC1 immunoprecipitated HDAC enzymatic activity and repressed transcription.