Homologous Superfamily

Paired amphipathic helix superfamily (IPR036600)

Short name: PAH_sf

Overlapping entries


This entry represents the paired amphipathic helix (PAH) repeat. Sin3 proteins have at least three PAH domains (PAH1, PAH2, and PAH3). They are components of a co-repressor complex that silences transcription, playing important roles in the transition between proliferation and differentiation. Sin3 proteins are recruited to the DNA by various DNA-binding transcription factors such as the Mad family of repressors, Mnt/Rox, PLZF, MeCP2, p53, REST/NRSF, MNFbeta, Sp1, TGIF and Ume6 [PMID: 11101889]. Sin3 acts as a scaffold protein that in turn recruits histone-binding proteins RbAp46/RbAp48 and histone deacetylases HDAC1/HDAC2, which deacetylate the core histones resulting in a repressed state of the chromatin [PMID: 14705930]. The PAH domains are protein-protein interaction domains through which Sin3 fulfils its role as a scaffold. The PAH2 domain of Sin3 can interact with a wide range of unrelated and structurally diverse transcription factors that bind using different interaction motifs. For example, the Sin3 PAH2 domain can interact with the unrelated Mad and HBP1 factors using alternative interaction motifs that involve binding in opposite helical orientations [PMID: 15235594].

Structurally, PAH2 is composed of four helices arranged in an open up-and-down bundle fold which binds alpha-helical peptides.

GO terms

Biological Process

GO:0006355 regulation of transcription, DNA-templated

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.