Interleukin-1beta converting enzyme(ICE)/inhibitor peptide complex
Homo sapiens (human)
Interleukin-1beta plays an important role in the process of blood clotting, immune response and inflammation. It has both paracrine signaling character, interacting with neighboring cells, and endocrine, hormone-like signaling character when carried through the blood. Interleukin-1 is released by macrophages and monocytes. Interleukin-1beta converting enzyme (ICE) is the protein that activates interleukin-1beta. ICE is a cysteine protease and is the first member of a new class of cysteine proteases that was recently discovered. Collectively these new cysteine proteases are known as caspases. They are prominently involved in process called apoptosis or programmed cell death, by which a cell is systematically destroyed through biochemical processes.
ICE has a distinct 3-dimensional structure that differs from the classic cysteine protease structure represented by papain. Papain has a central helix running through the whole molecule, with the active site cysteine at the end of that helix. In ICE the active site cysteine is located at the end of a beta strand. The beta strand is a member of six-stranded beta sheet in the center of the molecule. This sheet is sandwiched on either side by helices. Attached to the active site cysteine of ICE is an inhibitor, covalently bound to the cysteine sulfur, a peptide with four residues. This inhibitor was found by a new chemical technique and the structure determined to study the result in detail.
Protein Data Bank (PDB)