Technical Data
PBEF, Recombinant, Human (Pre-B cell Colony Enhancing Factor, Pre-B cell Enhancing Factor, 1110035O14Rik, DKFZP666B131, EC, MGC117256, Nicotinamide Phosphoribosyltransferase, NAmPRTase, NAMPT, Pre-B cell Colony Enhancing Factor 1, PBEF1, Visfatin
Molecular Biology Storage: -20CShipping: Blue Ice
Visfatin is a 55kD protein produced and secreted primarily by white adipose tissue. Recently, Visfatin was isolated from visceral fat deposits and shown to possess insulin-mimetic activity. Like insulin, Visfatin exerts hypoglycemic effects by interacting with the insulin receptor. The binding affinity of Visfatin for the insulin receptor is similar to that of insulin, but it does not compete with insulin, suggesting that the two proteins interact with different receptor sites.
The circulating levels of Visfatin are much lower than those of insulin and are not affected by feeding, implying that the hypoglycemic effect of Visfatin may not be of physiological importance. The plasma Visfatin levels, like those of Leptin, correlate positively with the percent of body fat and increase during the development of obesity. Another similarity between Visfatin and Leptin is that their amino acid sequence is highly conserved across different mammalian species and shows no homology to any known protein.
Receptors for both Leptin (Ob-R) and Visfatin (i.e. the insulin receptor) are expressed by neurons within the arcuate nucleus of the hypothalamus, a brain area that plays a pivotal role in the regulation of energy metabolism. Although the metabolic function of Visfatin is still unknown, it appears that this newly identified adipocytokine might play an important role, similar to that of Leptin, in the regulation of body weight, i.e. as an afferent signal reflecting excess body fat. Recombinant human Visfatin is a 52.5kD protein containing 465 amino acid residues (isoform 1).

Biological Activity:
The ED50 was determined by the dose-dependent proliferation of the RPMI 8226 cells. The expected ED50 for this effect is 15.0-20.0ng/ml.

Storage and Stability:
Lyophilized powder may be stored at -20C. Reconstitute with sterile 5mM sodium citrate, pH 2.8. For extended storage, add carrier protein (e.g., 0.1% BSA). Aliquot and store at -20C. Reconstituted product is stable for 3 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

Country of Origin:

Molecular Weight:
Source: E. coli
Purity: 98% by SDS-PAGE and HPLC analyses. Endotoxin:
0.1ng/ug (1EU/ug)
Form: Supplied as a lyophilized powder from 10mM Tris pH 8.0 and 25mM sodium chloride. Reconstitute with sterile 5mM sodium citrate, pH 2.8, to a concentration of 0.1-1mg/ml. Slow to dissolve. Do not vortex.

Important Note: This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.