Direct ELISA, Biotin-labelled antibody
Serum, Plasma-EDTA, Plasma-Heparin, Plasma-Citrate
Store the complete kit at 2–8°C. Under these conditions, the kit is stable until the expiration date (see label on the box).
Limit of Detection
n = 8; CV = 6.2%
n = 6; CV = 5.7%
- It is intended for research use only
- The total assay time is less than 4.5 hours
- The kit measures human GRP78 in serum and plasma (EDTA, citrate, heparin)
- Assay format is 96 wells
- Standard is recombinant protein based
- Components of the kit are provided ready to use, concentrated or lyophilized
Atherosclerosis, Autoimmunity, Cardiovascular disease, Energy metabolism and body weight regulation, Immune Response, Infection and Inflammation, Oncology
Human Glucose Regulated Protein 78 (GRP78) also known as BiP (immunoglobulin heavychain binding protein) or HSPA5 is a constitutively expressed protein from the HSP70 heatshock protein family. It exists in two isoforms, the standard isoform of 78 kDa constituted of 636 amino acids and the short GRP78 isoform of 62 kDa. Human GRP78 is a multifunctional protein involved in protein folding, calcium binding in the endoplasmic reticulum (ER), cellular defense mechanism, and antiapoptotic response of cells. It was reported to function as a cell-surface receptor in some cells. It is predominantly expressed in the ER, but it has also been found in other cellular compartments and in extracellular fluids. The expression of GRP78 is not tissue-specific. It is induced by hypoglycemia, hypoxia and some other cytotoxic stresses. Accordingly, elevated expression of
GRP78 was reported under pathological conditions in tissues with insufficient blood supply (e.g. myocardial infarction, pre-eclampsia, tumors), but also different nephropathies, neuropathies or atherosclerosis. It is believed to be one of the key regulators of cellular invasion and angioneogenesis in developing precancerous and cancerous tissues, and it has also been detected in the extracellular microenvironment of these tissues. Experiments in mouse models revealed that it is also required for optimal metabolic turnover of lipids and
glucose. GRP78 protein and its antibodies circulate in the blood of healthy individuals in small amounts.
The precise mechanism of GRP78 relocation from tissues into the blood stream is not fully understood, nevertheless, but concentrations of GRP78 in serum vary significantly within the population. The expression of different HSP proteins, including GRP78, is also elevated during inflammation. Consequently, the HSP proteins are released into the blood stream where they interact with different pro- and anti-inflammatory factors. Accordingly, the level of GRP78 protein and the level of anti-GRP78 antibodies were reported to be reproducibly increased in individuals suffering with rheumatic arthritis, a model autoimmune disease. In those individuals
GRP78 and its antibodies can also be detected in both synovial fluid and saliva.
Areas of investigation: Autoimmunity and inflammation, Cancer, Myocardial infarction, Atherosclerosis, Nephropathies, Neuropathies, Metabolic syndrome