Caspase 2

Caspase 2 also known as CASP2 is an is_associated_with::enzyme that, in humans, is encoded by the CASP2 is_associated_with::gene. CASP2 is_associated_with::orthologs have been identified in nearly all is_associated_with::mammals for which complete genome data are available. Unique orthologs are also present in is_associated_with::birds, is_associated_with::lizards, is_associated_with::lissamphibians, and is_associated_with::teleosts.

Function
Sequential activation of is_associated_with::caspases plays a central role in the execution-phase of cell is_associated_with::apoptosis. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme. The proteolytic cleavage of this protein is induced by a variety of apoptotic stimuli.

Caspase 2 proteolytically cleaves other proteins. It belongs to a family of is_associated_with::cysteine proteases called is_associated_with::caspases that cleave proteins only at an is_associated_with::amino acid following an is_associated_with::aspartic acid residue. Within this family, caspase 2 is part of the is_associated_with::Ich-1 subfamily. It is one of the most conserved caspases in different is_associated_with::species of animal. Caspase 2 has a similar amino acid sequence to initiator caspases, including is_associated_with::caspase 1, is_associated_with::caspase 4, is_associated_with::caspase 5, and is_associated_with::caspase 9. It is produced as a is_associated_with::zymogen, which contains a long is_associated_with::pro-domain that is similar to that of caspase 9 and contains a protein interaction domain known as a is_associated_with::CARD domain. Pro-caspase-2 contains two subunits, p19 and p12.

It has been shown to associate with several proteins involved in is_associated_with::apoptosis using its CARD domain, including RIP-associated Ich-1/Ced-3-homologue protein with a death domain (is_associated_with::RAIDD), is_associated_with::apoptosis repressor with caspase recruitment domain (ARC), and death effector filament-forming Ced-4-like apoptosis protein (is_associated_with::DEFCAP). Together with RAIDD and p53-induced protein with a death domain ([PIDD])(is_associated_with::LRDD), caspase 2 has been shown to form the so-called PIDDosome, which may serve as an activation platform for the protease, although it may also be activated in the absence of PIDD. In addition, caspase 2 may form a complex with the catalytic subunit of DNA-PK (is_associated_with::DNA-PKcs) and PIDD (is_associated_with::LRDD), which is involved in DNA repair after DNA damage. Overall, caspase 2 appears to be a very versatile caspase with multiple functions beyond cell death induction.

Interactions
Caspase 2 has been shown to interact with:
 * is_associated_with::BH3 interacting domain death agonist,
 * is_associated_with::CRADD,  and
 * is_associated_with::Caspase 8.