This family contains the paired amphipathic helix repeat. The family contains the yeast SIN3 gene Swiss:P22579 (also known as SDI1) that is a negative regulator of the yeast HO gene [1]. This repeat may be distantly related to the helix-loop-helix motif, which mediate protein-protein interactions.

1: The Saccharomyces cerevisiae SIN3 gene, a negative regulator of HO, contains four paired amphipathic helix motifs. Wang H, Clark I, Nicholson PR, Herskowitz I, Stillman DJ; Mol Cell Biol 1990;10:5927-5936. PMID:2233725