Figure 8
From: Structure of the SLy1 SAM homodimer reveals a new interface for SAM domain self-association
SAM domain interfaces in homodimers and homopolymers. Identical surfaces of two SAM monomers form the interface of symmetric SAM homodimers. The upper row shows the three types of SAM homodimers that have been reported. The termini-mediated EphA4 receptor SAM homodimer (PDB: 1B0X)16, the MAPKKK Ste11 SAM homodimer stabilized by interactions between amino acid residues in helices α4 and α5 (PDB: 1X9X)17, and the SLy1 SAM homodimer stabilized by interactions between amino acid residues in helices α1, α5 and the termini of both monomers (PDB: 6G8O). The monomer-monomer interface in a SAM homopolymer is formed by two different surfaces: the mid-loop (ML) surface of one monomer and the end-helix (EH) surface of the other monomer. This feature enables oligomerization. Three PHC3 SAM monomers that belong to a left-handed helical structure with six monomers per turn (PDB: 4PZO)75 are displayed in the lower panel.
