The cathepsin family of proteolytic enzymes contains several diverse classes of proteases. The cysteine protease class comprises cathepsins B, L, H, K, S, and O. The aspartyl protease class is composed of cathepsins D and E. Cathepsin G is in the serine protease class. Most cathepsins are lysosomal and each is involved in various cellular events such as peptide biosynthesis and protein degradation. The propeptide region of cathepsin H is highly homologous to other cathepsins. This region is

ICOS ligand is a member of the B7 family and the immunoglobulin superfamily. Human ICOS ligand is expressed by activated monocytes/macrophages and dendritic cells. It binds to a CD28 like receptor, inducible costimulator molecule (ICOS, AILIM, CRP-1), which is expressed by activated T cells. This interaction plays an important role in the T cell costimulation pathway.

BCL2L15 is a 163 amino acid protein and novel member of the Bcl-2 family that contains both BH2 and BH3 regions, but not BH1, BH4 or a C-terminal hydrophobic membrane anchor. Like Bcl-GL, Bfk does not bind to any Bcl-2 family members, even though its BH3 motif can mediate association with prosurvival proteins. Bfk localizes to cytoplasm, but unlike Bcl-GL, Bfk does not associate with organelles. Existing as four alternatively spliced isoforms, the pro-apoptotic isoforms of Bfk may help to pro

IL18 binding protein binds to IL18, prevents the binding of IL18 to its receptor, and thus inhibits IL18 induced IFN gamma production. It is constitutively expressed and secreted in mononuclear cells and can be enhanced by IFN gamma. An elevated level of this protein is detected in the intestinal tissues of patients with Crohn disease. Four alternatively spliced transcript variants encoding distinct isoforms have been reported.

The eight members of the recently identified Suppressor of Cytokines Signaling (SOCS) family are SOCS1, SOCS2, SOCS3, SOCS4, SOCS5, SOCS6, SOCS7, and CIS. Structurally the SOCS proteins are composed of an N- terminal region of variable length and amino acid composition, a central SH2 domain, and a C-terminal motif called the SOCS box. The SOCS proteins appear to form part of a classical negative feedback loop that regulates cytokine signal transduction. Transcription of each of the SOCS gene