Uncharacterized Archaeal homologs of Site-2 protease (S2P), zinc metalloproteases (MEROPS family M50) which cleave transmembrane domains of substrate proteins, regulating intramembrane proteolysis (RIP) of diverse signal transduction mechanisms. Members of the S2P/M50 family of RIP proteases use proteolytic activity within the membrane to transfer information across membranes to integrate gene expression with physiologic stresses occurring in another cellular compartment. In eukaryotic cells they regulate such processes as sterol and lipid metabolism, and endoplasmic reticulum stress responses. In prokaryotes they regulate such processes as sporulation, cell division, stress response, and cell differentiation. This group appears to be limited to Archaeal S2P/M50s homologs with additional putative N-terminal transmembrane spanning regions, relative to the core protein, and either one or two PDZ domains present.
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