NAMPT
Description
The NAMPT (nicotinamide phosphoribosyltransferase) is a protein-coding gene located on chromosome 7.
Nicotinamide phosphoribosyltransferase (NAmPRTase or NAMPT), formerly known as pre-B-cell colony-enhancing factor 1 (PBEF1) or visfatin for its extracellular form (eNAMPT), is an enzyme encoded by the NAMPT gene. The intracellular form (iNAMPT) is the rate-limiting enzyme in the NAD+ salvage pathway, converting nicotinamide to nicotinamide mononucleotide (NMN), responsible for most NAD+ formation in mammals. It can also catalyze NMN synthesis from phosphoribosyl pyrophosphate (PRPP) in the presence of ATP. eNAMPT acts as a cytokine (PBEF) activating TLR4, promoting B cell maturation, and inhibiting neutrophil apoptosis. iNAMPT catalyzes the reversible reaction: nicotinamide + 5-phosphoribosyl-1-pyrophosphate (PRPP) ⇌ nicotinamide mononucleotide (NMN) + pyrophosphate (PPi). This enzyme belongs to the glycosyltransferases, specifically the pentosyltransferases, and participates in nicotinate and nicotinamide metabolism. The liver has the highest iNAMPT activity, 10-20 times greater than kidney, spleen, heart, muscle, brain, or lung. iNAMPT is downregulated by increased miR-34a in obesity, reducing NAD(+) and SIRT1 activity. Endurance-trained athletes have twice the iNAMPT expression in skeletal muscle compared to sedentary type 2 diabetic individuals.
NAMPT is also known as 1110035O14Rik, PBEF, PBEF1, VF, VISFATIN.
