This enzyme is a member of a family of evolutionarily conserved cysteine protease proteins known as caspases. Many of these enzymes are part of a proteolytic cascade that plays a central role in cell death by apoptosis. Caspase-11 has been isolated and characterized as ICH-3 [ICE and CED3 homolog-3]. Caspase-11 gene expression in response to bacterial lipopolysaccharides and IFN-gamma requires NF-kappa-B and the signal transducer STAT1 .

By performing a yeast 2-hybrid assay to identify proteins that interact with CTD, Tanner et al. (1997) isolated partial cDNAs encoding SIP1, which they called CTD-associated SR protein 11 (CASP11) or SR-related protein of 129 kD (SRrp129). Northern blot analysis detected expression of the approximately 6-kb SRrp129 mRNA in all tissues tested.