CARDs are a subclass of protein motif known as the death fold, which features an arrangement of six to seven antiparallel alpha helices with a hydrophobic core and an outer face composed of charged residues.

[citation needed] A number of CARDs have been shown to play a role in regulating inflammation in response to bacterial and viral pathogens as well as to a variety of endogenous stress signals.

Ipaf-1 features an N-terminal CARD, a nucleotide-binding domain, and C-terminal leucine-rich repeats (LRRs), thought to function in a similar fashion to those found in Toll-like receptors.

[citation needed] Recently, a subset of CARD-containing proteins has been shown to participate in recognition of intracellular double-stranded RNA, a common constituent of a number of viral genomes, including the para- and orthomyxoviridae and rhabdoviridae.

Various studies have also demonstrated the involvement of several other signaling components in virus-induced activation of NF-κB and/or IRF3, including TRAF3, TRAF6, TANK, NEMO (IKKg), TRADD, FADD, and RIP (Kawai et al., 2005; Michallet et al., 2008; Oganesyan et al., 2006; Saha et al., 2006; Xu et al., 2005; Zhao et al., 2007).