Clusterin, Human, ELISA kit

Clusterin, or apolipoprotein-J, is an 80 kDa glycoprotein found in blood. It regulates processes like lipid transport, cell adhesion, and complement activity. It consists of two polypeptide chains linked by disulfide bonds and is expressed in most tissues. Different isoforms arise from its precursor, with secreted clusterin being the most common.

Clusterin, along with vitronectin and CD59, protects host cells from complement-mediated destruction by the membrane attack complex (MAC). It blocks C9 binding to C5b-8 and C5b-9. Additionally, it prevents C5b-7 from attaching to membranes, interrupting the complement cascade and preventing damage to cells. Its lipid-like properties likely contribute to its ability to inhibit MAC integration into cell membranes. A small fraction of clusterin dissociates from sTCC in the presence of detergents, which may explain its partial activity. The amount of active heterodimeric clusterin is reported to be less than 10%. This makes its effectiveness dependent on local conditions and the presence of other complement inhibitors.

In addition to complement regulation, clusterin is linked to diseases such as Alzheimer’s, atherosclerosis, and autoimmune disorders. For instance, clusterin levels are elevated in early rheumatoid arthritis but reduced in some psoriatic patients.