| Type: | Domain | Name: | Sterile alpha motif domain |
| Description: | The sterile alpha motif (SAM) domain is a putative protein interaction module present in a wide variety of proteins [] involved in many biological processes. The SAM domain that spreads over around 70 residues is found in diverseeukaryotic organisms []. SAM domains have been shown to homo- and hetero-oligomerise, forming multiple self-association architectures and also binding to various non-SAMdomain-containing proteins [], nevertheless with alow affinity constant []. SAM domains also appear to possess the ability to bind RNA []. Smaug, a protein that helps to establish a morphogen gradient in Drosophila embryos byrepressing the translation of nanos (nos) mRNA, binds to the 3' untranslated region (UTR) of nos mRNA via two similar hairpin structures. The 3D crystalstructure of the Smaug RNA-binding region shows a cluster of positively charged residues on the Smaug-SAM domain, which could be the RNA-binding surface. This electropositive potential is unique among all previouslydetermined SAM-domain structures and is conserved among Smaug-SAM homologues. These results suggest that the SAM domain might have a primary role in RNA binding.Structural analyses show that the SAM domain is arranged in a small five-helix bundle with two large interfaces []. Inthe case of the SAM domain of EphB2, each of these interfaces is able to form dimers. The presence of these two distinct intermonomers binding surface suggest that SAM could form extended polymeric structures []. | Short Name: | SAM |
