The precursor polypeptide chain is cleaved proteolytically to remove the 22-mer secretory signal peptide and subsequently between residues 227/228 to generate the a and b chains. These are assembled in anti-parallel to give a heterodimeric molecule in which the cysteine-rich centers are linked by five disulfide bridges and are flanked by two predicted coiled-coil a-helices and three predicted amphipathic a-helices.
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, 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 Clusterin Rat His-Tagged Fusion Protein, produced in E.coli, is 26.5kDa protein containing 215 amino acid residues of the APO-J Rat and 25 additional amino acid residues: N-terminal fusion of T7-Tag (16AA) and C-terminal fusion of His-Tag (9AA). (Underlined).
Filtered (0.4µm) and lyophilized from 0.5mg/ml in 0.02M Tris buffer and 0.05M NaCl, pH 7.5.
It is recommended to add deionized water to a working concentration of 0.5mg/ml and let the lyophilized pellet dissolve completely. Product is not sterile! Please filter the product by an appropriate sterile filter before using it in the cell culture.
Greater than 90% as determined by SDS PAGE.
Amino acid sequence
MASMTGGQQM GRDPNSSSPF YFWMNGDRID SLLESDRQQS QVLDAMQDSF TRASGIIDTL FQDRFFTHEPQDIHHFSPMG FPHKRPHLLY PKSRLVRSLM PLSHYGPLSF HNMFQPFFDM IHQAQQAMDV QLHSPALQFPDVDFLKEGED DRTVCKEIRH NSTGCLKMKG QCEKCQEILS VDCSTNNPAQ ANLRQELNDS LQVAERLTQQYNELLHSLQS KMLNTSSLLE QALEHHHHHH.