Visfatine (NAMPT)

Visfatin is a 55 kDa 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 52.5 kDa protein containing 465 amino acid residues (isoform 1) .

NAMPT; VF; PBEF; PBEF1; VISFATIN; 1110035O14Rik

10135

P43490

NP_005737.1

NM_005746

7q22.3

Human

Human

MPPNTSKVYS YFECREKKTE NSKLRKVKYE ETVFYGLQYI LNKYLKGKVV TKEKIQEAKD VYKEHFQDDV FNEKGWNYIL EKYDGHLPIE IKAVPEGFVI PRGNVLFTVE NTDPECYWLT NWIETILVQS WYPITVATNS REQKKILAKY LLETSGNLDG LEYKLHDFGY RGVSSQETAG IGASAHLVNF KGTDTVAGLA LIKKYYGTKD PVPGYSVPAA EHSTITAWGK DHE kDaFEHI VTQFSSVPVS VVSDSYDIYN ACEKIWGEDL RHLIVSRSTQ APLIIRPDSG NPLDTVLKVL EILGKKFPVT ENSKGYKLLP PYLRVIQGDG VDINTLQEIV EGMKQKMWSI ENIAFGSGGG LLQKLTRDLL NCSFKCSYVV TNGLGINVFK DPVADPNKRS KKGRLSLHRT PAGNFVTLEE GKGDLEEYGQ DLLHTVFKNG KVTKSYSFDE IRKNAQLNIE LEAAHH

< 0.1 ng/µg of protein (< 1EU/µg)

> 98% by SDS-PAGE & HPLC analyses

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

466

Lyophilized

52.6 kDa

E. coli