InterPro domain: IPR015316

The fungal Ste50 SAM domain consists of five helices, which form a compact, globular fold. It is required for mediation of homodimerisation and heterodimerisation (and in some cases oligomerisation) of the protein [ 1 ].

Ste50-like proteins have a SAM domain at the N terminus and Ras-associated UBQ superfamily domain at the C terminus. They participate in regulation of mating pheromone response, invasive growth and high osmolarity growth response, and contribute to cell wall integrity in vegetative cells. Ste50 of S.cerevisiae acts as an adaptor protein between G protein and MAP triple kinase Ste11. Ste50 proteins are able to form homo-oligomers, binding each other via their SAM domains, as well as heterodimers and heterogeneous complexes with SAM domain or SAM homodimers of MAPKKK Ste11 protein kinase [ 2 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ].

1. Structure of the sterile alpha motif (SAM) domain of the Saccharomyces cerevisiae mitogen-activated protein kinase pathway-modulating protein STE50 and analysis of its interaction with the STE11 SAM. J. Biol. Chem. 279, 2192-201
2. SAM domain-based protein oligomerization observed by live-cell fluorescence fluctuation spectroscopy. PLoS ONE 3, e1931
3. Saccharomyces cerevisiae Ste50 binds the MAPKKK Ste11 through a head-to-tail SAM domain interaction. J. Mol. Biol. 356, 142-54
4. The RA domain of Ste50 adaptor protein is required for delivery of Ste11 to the plasma membrane in the filamentous growth signaling pathway of the yeast Saccharomyces cerevisiae. Mol. Cell. Biol. 26, 912-28
5. The solution structure of the S.cerevisiae Ste11 MAPKKK SAM domain and its partnership with Ste50. J. Mol. Biol. 342, 681-93
6. Solution structure of the dimeric SAM domain of MAPKKK Ste11 and its interactions with the adaptor protein Ste50 from the budding yeast: implications for Ste11 activation and signal transmission through the Ste50-Ste11 complex. J. Mol. Biol. 344, 1071-87
7. Adaptor protein Ste50p links the Ste11p MEKK to the HOG pathway through plasma membrane association. Genes Dev. 20, 734-46
8. STE50, a novel gene required for activation of conjugation at an early step in mating in Saccharomyces cerevisiae. Mol. Gen. Genet. 236, 145-54
9. The role of adaptor protein Ste50-dependent regulation of the MAPKKK Ste11 in multiple signalling pathways of yeast. Curr. Genet. 43, 161-70