Predicted pore-forming effector domain found in conserved genome contexts with diverse nucleotide synthetases including the SMODS synthetases. Predicted to function as a pore-forming effector in a class of conflict systems reliant on the production of second messenger nucleotide or nucleotide derivatives. S-4TM domains are predicted to initiate cell suicide responses upon their activation [1].

1: Comparative genomic analyses reveal a vast, novel network of nucleotide-centric systems in biological conflicts, immunity and signaling. Burroughs AM, Zhang D, Schaffer DE, Iyer LM, Aravind L; Nucleic Acids Res. 2015;43:10633-10654. PMID:26590262