Description
Clusterin also named Apoliprotein J (APO-J) is a 75-80 kD disulfide-linked heterodimeric protein. Across a broad range of species clusterin shows a high degree of sequence homology ranging from 70% to 80%. It is nearly ubiquitously expressed in most mammalian tissues and can be found in plasma, milk, urine, cerebrospinal fluid and semen. It is able to bind and form complexes with numerous partners such as immunoglobulins, lipids, heparin, bacteria, complement components, paraoxonase, beta amyloid, leptin and others. Clusterin has been ascribed a plethora of functions such as phagocyte recruitment, aggregation induction, complement attack prevention, apoptosis inhibition, membrane remodeling, lipid transport, hormone transport and/or scavenging as well as matrix metalloproteinase inhibition. A genuine function of clusterin has not been defined. One tempting hypothesis says that clusterin is an extracellular chaperone protecting cells from stress induced insults caused by degraded and misfolded protein precipitates. Clusterin is up- or down regulated on the mRNA or protein level in many pathological and clinically relevant situations including cancer, organ regeneration, infection, Alzheimer disease, retinitis pigmentosa, myocardial infarction, renal tubular damage, autoimmunity and others. The recombinant rat ApoJ/Clusterin was constructed with an N- terminal T7-Tag fusion (16AA) and a C-terminal His-Tag fusion (9AA). This His-tagged fusion protein produced in E.coli has a molecular weight of 26.5 kDa containing 215 amino acid residues of the APO-J Rat and 25 additional amino acid residues (His-Tag, T7-Tag)