This is a family of the conserved N-terminal end of a group of proteins conserved in fungi. It is likely to be a Sin3 binding protein. Sin3p does not bind DNA directly even though the yeast SIN3 gene functions as a transcriptional repressor. Sin3p is part of a large multiprotein complex. Stb3 appears to bind directly to ribosomal RNA Processing Elements (RRPE) although there are no obvious domains which would accord with this, implying that Stb3 may be a novel RNA-binding protein.