PBEF also known as Visfatin, NAMPT is a member of the nicotinic acid phosphoribosyltransferase (NAPRTase) family. PBEF plays a crucial role in the biosynthesis of nicotinamide adenine dinucleotide (NAD), a vital coenzyme involved in numerous metabolic processes, including energy production and cellular signaling. PBEF catalyzes the conversion of nicotinamide and 5-phosphoribosyl-1-pyrophosphate into nicotinamide mononucleotide, marking a rate-limiting step in the NAD biosynthesis pathway. This function is particularly important as NAD is essential for the activity of various enzymes, including sirtuins, which are implicated in aging and metabolic regulation. PBEF is predominantly expressed in the cytoplasm and is highly enriched in visceral fat, with expression levels in plasma increasing during obesity development, highlighting its potential role in metabolic disorders.